[Galaxy Note 10.1 General] X-Stranger:
For anyone interested, below are the steps for getting your device dual-booting with CyanogenMod 10.2.

Why?

I don't want to erase native firmware and want to give a try to CyanogenMod

I want to have both native and CM, because I like native Samsung S-Pen apps, but want to have more fresh Android too

I like experimenting - it's cool!

The Idea

Our Android device has 2 boot partitions - for normal boot, and to boot into recovery. If I want to boot CyanogenMod, I need to place its boot image instead one of those boot partitions. E.g. if I want to have both native firmware and cyanogen - then obviously I need to replace recovery partition. However I can do the backup of recovery and restore it later if needed.

But, I also need to place cyanogen system and data partitions somewhere. Putting it on the external sdcard makes CM working really slow, repartitioning internal memory might be good idea, but it is not so easy and is not necessary for experimenting. Thus I've created 2 image files and put it to native data partition (mmcblk0p12) to media folder, e.g. into internal sdcard, then changed cyanogen boot image to mount those image files on boot as system and data partitions.

Prerequisites:

Rooted Samsung Galaxy Note 10.1 2012 Edition

2GB of free disk space at internal sdcard

Recovery partition backup, because we are going to replace it with CyanogenMod boot image

Clear understanding of what you are doing, because you potentially can break your device

Downloads:

CM 10.2 boot image

CM 10.2 data partition image

CM 10.2 system partition image

Steps

This manual suggests that you are going to do the recovery backup to external sdcard and has native firmware which means that recovery partition is mmcblk0p6, data partition is mmcblk0p12 and internal sdcard is /mnt/sdcard folder (otherwise you need to change the commands appropriately and might need to fix cyanogen boot image too).

Download 3 files by the links above and upload to internal sdcard of your device. Connect to your device via ADB and run ADB shell, or type the next commands in terminal emulator:

# become root
su -

# go to external sdcard to create recovery backup
cd /mnt/extSdCard
dd if=/dev/block/mmcblk0p6 of=./recovery.img

# go to internal sdcard folder
cd /mnt/sdcard

# unpack partition images - each is 1Gb of disk space
gunzip ./system.img.gz
gunzip ./data.img.gz

# write CM boot image to recovery partition
dd if=./cyanogen.img of=/dev/block/mmcblk0p6

# finish
exit
exit

Now you can reboot your device into recovery mode and see CyanogenMod booting.

Restoring native recovery:

If you got tired from CyanogenMod and/or would like to take back your recovery, please use the backup you've done before. Lets say it is placed on your external sdcard, then connect to your device via ADB and run ADB shell, or type the next commands in terminal emulator:

# become root
su -

# go to the folder with recovery backup
cd /mnt/extSdCard

# write recovery image over recovery partition
dd if=./recovery.img of=/dev/block/mmcblk0p6

Please let me know If I missed anything in my steps.

P.S. What I've changed in Cyanogen boot.img to make it using img files instead of partitions in form of patch: View attachment 2519229. It is also necessary to create /host folder in initrd folder tree.