Having successfully flashed Jelly Bean 4.1.1 to my Tab 2 10.1 P5110, I thought I‘d share the procedure I used and the notes I made. Actually I’ve flashed two and have a third to do, that’s what happens when you get something like this and family see what it can do.
These steps assume you've flashed firmware before with odin, if not there are plenty of guides already available. These are the steps I took for my preferred result, which was stock firmware, rooted, ClockWorkMod recovery, battery mod & flash counter reset. I also installed Adobe Flash.
If you don't agree, feel free to do it your own way. I prefer to use my laptop for flashing as it's unaffected by power cuts. Download mode is vol up & power, recovery is vol down & power (the opposite to our phones).
1. Backup everything. Internal 'sdcard', apps & data using Titanium Backup (if already rooted), screenshots, also any apps with their own in-built backup. Remove external sdcard.
2. Clear cache, Dalvik cache and factory reset, all in recovery.
3. Flash XXCLK7 Jelly Bean using odin, firmware downloaded from SamMobile.
4. Factory reset in system menu.
5. Flash Chainfire's CF-Root, available from XDA, as PDA in odin. LINK
6. Flash CWM recovery, available from XDA, as PDA in odin. CF-Root above resets the stock recovery so do it in this order. See *Note below. LINK
7. Install battery mod (or other mod) in recovery. I use UOT Kitchen which is a doddle. LINK
8. Use Chainfire's TriangleAway app to reset the flash counter. LINK
9. Stick the sdcard back in, copy back app data or media to the internal 'sdcard', adjust settings, reinstall apps. I use Titanium Backup which puts practically every app back as it was before.
10. Install Adobe mobile Flash apk. Can't recall where I got this from, but a quick search should find the latest copy.
Time taken - a few hours. JB is certainly smoother than ICS and has removed the stutter I had when using live wallpaper and scrolling home screens.
*Note: As of 4.0.4 the recommendation was to untick the auto reboot option in odin, flash, remove cable and manually reboot into recovery using vol down & power (release power when screen comes on). This was to get past the tablet resetting itself to stock recovery before CWM could be established, or something like that. Anyway, I've continued this procedure with JB and it worked fine.