In order to do this, you need to have your bootloader unlocked and fastboot working. If you haven't already see here:
Files to download:
Works with both ICS and JB...
The guide is intended for Windows users. I know some have gotten this to work in Linux, maybe someone can write a guide for Linux.
Why unlock your bootloader?
In order to install ClockworkMod recovery (or any other custom recovery), root, install custom ROMs or custom kernels you need an...
I've updated my ROM for the A2109 to Jelly Bean.
Based on Lenovo's stock Jelly Bean 4.1.1 ROM
Deodexed (allows modding/theming)
Do not install the stock JB update if you root or run custom ROMs... it breaks CWM recovery.
I'm working on a fix... it looks like they changed the partition structure such that CWM can't mount anything.