Final Fantasy Hacktics

I am using Cloud's base and Death Knight Argath's pants

Tell me what you think.

First time, so all I'm doing is copying and pasting with a little bit of editing

So, I have already extracted the fftpack.bin and replaced the sprites I want.

But how do I put it back into the iso?

I rebuilt or repacked it so it is fftpack.bin. How do I put it into the iso? UMDGen didn't work. I deleted the original fftpack.bin and replaced it with mine. Then I have to save, I saved it as an .iso. I loaded it on my psp and it crashed. The file size on the new one was way different than the original .iso.

How do I put these sprites in?

A link or advice would be helpful.

Thanks

Oh and if I need to give more info just ask....