you need to root the device before doing anything....
then, you have to use nandroid to backup your current firmware
finally, take a custom rom (I used beHero), and flash it doing the usual procedure (found online, with the tools provided by the rooted image)
it doesnt take more than 20 minutes to do the whole proccess... I would give you more info, but i have in a right now "non-usable" computer... sorry
search for it in google, and you'll find sth like that... the needed tools are in xda-developers (i think), and the roms are available (you should choose one that fits your needs)