IIRC, the gsm pre2 uses a different bezel,so its a slightly different process.
Also, supposedly using a gsm pre2 will allow you to get ota updates straight from palm (I'd any ever come).
As a word of warning, I've done this (I used a vzpre2), and there was a period of time that palm made some changes in their servers and I couldn't access 2.x apps.. So try to use impostah to activate your new phone, so it will be viewed as a pre2, rather than a pre+, to plan's .servers I think this is possible, but don't quote me. :-)
Good luck, and I think this is a great idea that I encourage everyone to do!
(hm, I wonder if a vzpre2 bought in the beginning,that came with free mhs, would still eligible for free mhs with a new owner. Probably not, but.. Hmm..)
Aside, I like freetether as I like to tether over USB. I was in discussion (before I changed phone companies) with puff about adding support to his app for using the MHS data allowance and it seemed possible, but someone with mhs would have to work with him on it. As it stands, installing freetether will disable your built-in mhs app.