[Galaxy Tab 2 (Unified 7" + 10.1") Android Developm] pWEN:
I'll post the full instructions that I used before. It's lengthy, but I try to be detailed to avoid confusion. You may need to do some research to find updated files that are more relevant to your model of tablet. The process should be about the same, though, so you can use these instructions as a general guide.

Recovery: power + volume up while tablet is off.

Download/fastboot: power + volume down.

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PRE-REQUISITES

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Tablet: Enable USB debugging

Java: Latest JRE and JDK for x86 and x64

Development Software: installer_r24.3.4-windows.zip (Android SDK Tools)

Flashing Software: Odin3-v1.85.zip

Drivers: SAMSUNG_USB_Driver_for_Mobile_Phones_v1.5.45.0.exe

Stock ROM: XAR-P3113UEUCMK3-201312111144623.zip (4.2.2)

Rooting Software: CF-Auto-Root-espressowifi-espressowifiue-gtp3113.zip

Custom Recovery: GT-P3110_CWM_6.0.5.1.zip (ClockworkMod) -OR- GT-P3110_TWRP_2.8.7.1.zip (Team Win Recovery Project)

Custom ROM: Slim-p3110-4.4.4.build.9.0-OFFICIAL-8291.zip (SlimKat 4.4.4 build 9)

GApps: Slim-Addons-mini_gapps.4.4.4.build.9-20150107.zip

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OVERVIEW

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Note: Each step assumes you have completed the previous step

1. Install drivers and software

2. Flash stock ROM

3. Root

4. Flash recovery

5. Flash custom ROM

6. Flash GApps

7. (Optional) Flash custom kernel

8. Thread links

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1. INSTALL DRIVERS AND SOFTWARE

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Note: If you're on Windows 8, you'll first need to do an advanced reboot with driver signing turned off.

1.1) Turn on the tablet, make sure an external SD card is inserted, and enable USB debugging

1.2) Install the latest Java JRE and JDK for x86 and x64

1.3) Add locations to the JDK to your PATH variables:

- Go to Control Panel > System > Advanced Settings > Environment Variables

- Add the location to the JDK's bin folder to the end of the PATH variable (C:\Program Files\Java\jdk1.6.0_27\bin)

1.4) Extract the Android SDK Tools to an easy-to-access location (such as C:\AndroidSDK)

1.5) Open the SDK Manager (C:\AndroidSDK\SDK Manager.exe)

1.6) Select "Android SDK Tools", "Android SDK Platform-tools", and "Android SDK Build-tools", and install the packages

1.7) Add ADB to Windows command prompt:

- Go to Control Panel > System > Advanced Settings > Environment Variables

- Add a new System Variable called ADB_HOME, pointed to the Android SDK's platform-tools folder (C:\AndroidSDK\platform-tools)

- Add %ADB_HOME% to the end of the PATH variable

1.8) Extract Odin to an easy-to-access location

1.9) Extract and install the tablet drivers

1.10) Extract the MD5 or TAR from inside the firmware ZIP file

1.11) Plug the tablet into the computer and make sure it is recognized

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2. FLASH STOCK ROM

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2.1) Unplug the tablet, turn it off, then hold down POWER and VOL UP to reboot into recovery

2.2) Choose "wipe data/factory reset"

2.3) Choose "wipe cache partition"

2.4) Unplug the tablet, turn it off, then hold down POWER and VOL DOWN to boot into Download/fastboot mode

2.5) Open Odin

2.6) Click the PDA button, then select the stock ROM MD5 or TAR

2.7) Make sure Repartition is NOT checked, then click Start

2.8) When it's done, disconnect the tablet and reboot into the OS

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3. ROOT

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3.1) Unplug the tablet, turn it off, then hold down POWER and VOL DOWN to boot into Download/fastboot mode

3.2) Extract the contents of the AutoRoot zip

3.3) Start Odin (the newer version you extracted earlier, not the one included with the AutoRoot)

3.4) Click the PDA button in Odin and select the *.tar.md5 file extracted from the AutoRoot zip

3.5) Connect the tablet to the computer, and Odin should report being able to recognize the device

3.6) Make sure Repartition is NOT checked, then click Start

3.7) When it's done, disconnect the tablet and reboot into the OS

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4. FLASH RECOVERY

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4.1) Unplug the tablet, turn it off, then hold down POWER and VOL DOWN to boot into Download/fastboot mode

4.2) Extract the contents of the AutoRoot zip

4.3) Start Odin (the newer version you extracted earlier, not the one included with the AutoRoot)

4.4) Click the PDA button in Odin and select the *.tar.md5 file extracted from the AutoRoot zip

4.5) Connect the tablet to the computer, and Odin should report being able to recognize the device

4.6) Make sure Repartition is NOT checked, then click Start

4.7) When it's done, disconnect the tablet and reboot into the OS

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5. FLASH CUSTOM ROM

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5.1) Unplug the tablet, turn it off

5.2) Hold down POWER and VOL UP to boot into recovery

5.3a) If in CWM: do a factory reset, wipe cache, go to Mounts and Storage and format system.

5.3b) If in TWRP: go to Wipe and choose advanced, wipe Dalvik, cache, system, and data

5.4) Choose to flash a ZIP

5.5) Browse to SD card

5.6) Select custom ROM file and and continue

5.7) When done, wipe dalvik/cache

5.8) If flashing GApps, proceed to: 6. FLASH GAPPS. Otherwise, reboot system.

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6. FLASH GAPPS

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6.1) Choose to flash a ZIP

6.2) Browse to SD card

6.3) Select GApps file and continue

6.4) When done, reboot

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7. FLASH CUSTOM KERNEL

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7.1) Choose to flash a ZIP

7.2) Browse to SD card

7.3) Select the kernel file and continue

7.4) When done, reboot

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8. THREAD LINKS

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Android-Andi Slim builds

http://andi34.github.io/

Frequently Asked Questions

http://xdaforums.com/showthread.php?t=2182096

CF Auto-Root

http://xdaforums.com/showthread.php?t=1957160

Recoveries

http://xdaforums.com/showthread.php?t=2548257

TWRP

https://dl.twrp.me/p3110/

OpenGApps

ARM > 4.4 > pico

http://opengapps.org/