Last night I started work on a new feature for the code converters on the systems' home pages. It will basically help you create codes, it may be especially helpful with the later consoles that have complicated codetypes and whatnot. It's in beta right now, and presented as-is. I can't guarantee its accuracy, as it's not too smart on what the devices can and can't support. (e.g. all the different types of conditionals, or math operations.) Anyway, it's a good starting point.

You select the device and whether you want the code to be encrypted as usual, then choose a codetype and input the parts in the form that appears. Easy-peasy.

It should be working for all systems, but here is a link to PS2 anyway.
http://gamehacking.org/?sys=ps2

Play around with it, post grievances/high praise in this thread here.