It’s been about a year since I did this so things may have changed or I might be forgetting stuff, but after spending ages trying to follow step by step guides I eventually discovered SuperOneClick which basically did everything for me so would second that suggestion, and also as mentioned above the xda-developers forum can answer pretty much any question you have too.
munkster: Have you read up on “a2sd” yet? I had to download a terminal emulator app and type ‘a2sd install’ or something to get it to use the ext4 partition for apps. If you’re choosing the “move to SD” option in the apps list you’re doing it wrong I think. Also, the available space display didn’t work properly for me using a2sd, but I never seemed to run out of space no matter what it said, and running the command ‘df’ in the terminal app should show how much space is left on each partition. You might have already tried this or things might have changed since I did it but good luck 🙂