here is what i learned
1) once you get the thing rooted, you have to install a "recovery" method. you have a choice between "clockworkmod" and "Amon_Ra". I chose Clockwork, but Amon_Ra is all that works with Fresh. I am consequently changing my recovery method in a second.
2) Then follow the instructions to get back to a fully rooted/stock 2.2. This is the end of the instructions on the XDA website.
3) Once you are done with the instructions, go to the XDA website and d/l the new fresh rom, as well as the new radio roms.
4) Put the phone in boatloader mode, then into recovery, then choose "nandroid" and then create backup. This is your safety net, or so it seems.
5) once you have created a nandroid backup, you need to select the option for "wipe phone/factory reset" which does exactly that. your operating system won't change, but all your data will be gone.
6) after you have wiped the phone, chose the "flash rom" option and select the "fresh" zip. then reboot. It took a solid 2 minutes for my phone to work through it, but I fought the urge to pull the battery and was rewarded.
7) once you are up and running, go back to boatloader>recovery>flash rom> then chose the radio update. then reboot.
8) redo item 7, but with selecting the wimax radio update.
then you should be up and running with the latest Fresh
PS, no warranties. Root at your own risk!!