(13/01/2012 04:11 PM)lacrimosaangel Wrote:  Once I have that theme, how would I then go about converting the ctf to 6.60 compatibility

You generally wouldn't need to convert it as such.
Consider this: when Sony changes their firmware, they sometimes introduce new icons and remove others.  This means that there'll either be more or less icons or other resources in the RCO files.  PRX files almost always change between firmwares.
So if you've got a theme for 5.00, it probably won't work on 6.60 due to it lacking required icons or PRXes being completely different.
However, if you're working off a 6.60 base, then you don't need converting at all.  If you're trying to get a 5.00 theme to work on 6.60, you'll need to convert by putting in the new resources, and shifting the modded PRX values over to a 6.60 base.

(13/01/2012 04:11 PM)lacrimosaangel Wrote:  and how do I change the click sounds and bootup sounds?

Click sounds are stored in RCOs (system_plugin.rco from memory) as VAG files.  Rcomage has a WAV«>VAG converter built in, though I'm a little dubious over its quality.
Boot sound is in opening_plugin.prx I think - check a guide on how to mod that.

(13/01/2012 04:11 PM)lacrimosaangel Wrote:  I read somewhere about just replacing the .prx files within the ctf, but I don't see anywhere to do that on these programs I have downloaded?

Basically means to decompile the CTF, replace the PRXes, then compile again.
So, for example, you extract C:\mytheme.ctf to C:\mytheme-files\, replace/mod the PRXes in C:\mytheme-files\, then compile everything in C:\mytheme-files\ into a CTF.