[AT&T Samsung Galaxy S II Skyrocket SGH-I727] KAPABLE-K:
I have the skyrocket and also the HD

Below is the instructions to install CWM and root on the S2 HD LTE. (credit to the user dsixda)

Get the required files here

To install CWM Recovery:

If you don't already have Odin, download it from the link above, and extract the zipped file to a folder. Ensure both the .EXE and .INI file have been extracted.

Download the TAR file for ClockWorkMod Recovery (e.g. cwm_recovery_xxxx.tar, or if you want the version that uses finger touch input: cwm_touch_recovery_xxxx.tar). Do not extract the file out of it, keep the TAR file as it is.

Turn off the phone

Put it into Download mode by pressing Power and Volume Down at the same time. The device will vibrate and soon you will see a Warning screen, where you will need to press Volume Up to enter Download mode. (NOTE: You can also use the Galaxy S2 USB Jig to go straight to Download mode. I recommend you get one from eBay just in case.)

While in Download mode, start up Odin and connect your phone to the PC via USB. You should see a status message in Odin saying your device was "added".

In Odin, press the BOOTLOADER button and select the CWM TAR file you just downloaded.

In Odin, press Start. Your custom recovery should be flashed completely in a span of a few seconds, and then it should say "PASS" in Odin. If it doesn't finish and is stuck, then your file was either corrupted during the download or there was an MD5 mismatch (this is not a regular TAR file, it has an MD5 signature).

IMPORTANT: If you downloaded the "Touch" version of CWM, *avoid* using the "Reboot to Recovery" option in the ROM or apps like Quick Boot to boot into recovery. I have found that using such apps with Touch Recovery causes every subsequent reboot to go back into recovery rather than to the system. If you are stuck in this state, re-flash the recovery image so that it boots back to the system. Next time, if you want to get into recovery, use the button combination mentioned in the steps below instead. If you have the non-touch (normal) version of CWM, this issue won't happen.

To enter CWM Recovery:

Turn off the phone

Hold down the Power button to turn the phone on, and then immediately hold down Volume Up + Volume Down at the same time.

The device will then show the word "Samsung". Let go of the buttons at the exact moment you see this.

If you did it on time, you will enter CWM Recovery. Use the Volume keys to move up and down, and press Power to select. The capacitive buttons do this: Menu = DOWN, Back = BACK to main menu, Search = SELECT

NOTE: If you had flashed CWM but are still seeing the stock recovery image, then re-flash CWM and afterwards pull the USB cable immediately after seeing 'PASS' in Odin, while the phone's screen is black. Then do the button combo shown above to get into CWM.

Make sure you make a Nandroid backup of everything the first time you use custom recovery. The backup will be stored under the 'clockworkmod' folder of your SD card.

To root your device through CWM:

This step is only if you want to root the stock firmware that is currently on your device. If you are going to flash a ROM like CyanogenMod, then you can skip this section, since most custom ROMs already have root installed.

You need to first download root_sgs2hdbell.zip from the Dev-Host site linked above. Copy it to your device's internal or external SD card.

Then go back into CWM and flash the ZIP. You should now be rooted, you don't need to do anything else to your stock ROM.