You can also follow the instructions on here which are MUCH easier IMO
Then do the Voodoo OTA rootkeeper, unroot, take the update, then reroot. This solved my problems in a matter of minutes, when searching through these threads for days trying to find the info was getting me nowhere fast.
the method posted by Import will only work if they havent applied the jb update before you get it. i think the version will be 4.0.4 if its ics.
if it says 4.1.2, they already applied jb and you will have to use the method Chuck posted, more precisely here Easy Root for Bionic Stock 4.1.2 (Jelly Bean)
the ics root will not work on jb, dont waste your time trying.
Been doing some digging around on the web and cant seem to find a decent way to root my bionic thats on jellybean. the reason is because all the ways to root that ive seen require wifi. im sending my phone back to verizon and had my phone rooted on ics but then i unrooted and updated to jellybean. now on jb i have no access to wifi thus why i am sending back my phone to verizon for a new phone. any comments or anything would be appreciated. i need to fix this asap so please help