What is the best way to shrink or take things off a .ISO or .CSO that I don't need. Please help me out, I need help asap!!

Use UMDGen (v4.00): http://www.psp-hacks.com/file/948
You can remove, replace or re-link files that you don't need.
Make sure you take a backup first though.

Alternatively, you could find a rip-kit specific to the game, but then you might not get full control over what you are removing.

is it available for mac?

I don't think so.
You might want to look here though: http://forums.maxconsole.net/showthread.php?t=26001

thanks for that dude, really helpful

thats cool thx alot