How do I back up the GT540's ROM?

[Guest asmarinian]

I want to try out some different ROMs but I want a full backup of my phone. As many of you probably know already, clockwork's ROM manager does not include the GT540 under the list of phones, so I don't know what else to do. Any help would be much appreciated.

Also, my post "phone keeps crashing randomly" has new [potentially important] info.