I just got an email form someone asking me how I did this and whether I could help them also do it.  Unfortunately, as far as I know, there is no easy way of doing this, unless you happen to work at Microsoft! :)  And even then, its probably not easy to do anymore since the beta program is now closed.  I joined the original beta program for Windows Mobile 5 and one of the supported phones was the SMT5600.  I purchased it unlocked and went and upgraded it.  Because the boot loader is locked (different from a SIM lock), its not an easy process and I wouldn't recommend any of the stuff floating out there as it could void your warranty, is probably illegal, not to mention "brickify" your phone.