Synch your bookmarks over to a PC, rearrange the order in Chrome, then sync the bookmarks back to the xoom.
I have 2 profiles for chrome synch, a mobile one for my evo and xoom, and another for my personal and work PC bookmarks. Do all the arranging on a regular PC and synch it back, then change the PC profile back if you have more than 1 set of bookmarks synched.