1. dump your registry
2. toss it in this folder
3. hex edit to your heart's content
4. run 'fixupdreg3' to fix the checksums
5. write your registry back to the PSP

you can also double-click reg2xml to dump an XML version of your registry. open it up in pretty much any web browser other than IE to see it displayed in a table. this can be really useful for figuring out what to hex edit to change various settings.