I'm assuming it's Zero Suit Samus.
What you need to do is either open the common.pac (if it's not common.pac, then it's common4.pac), and replace the FitSZeroSuitMotionEtc with your FitSZeroSuitMotionEtc.pac or use Project M's common.pac and common4.pac then just insert the FitSZeroSuitMotionEtc.pac into the szerosuit folder.
Observant you are. ^^ Sorry to have you running all over the forums like this.
I do understand where I need to replace it, it's getting there. I do not know where the common4.pac is located in the ISO directory structure.
I have Partitions 0-13 with Partition 1 containing the fighter folder. I've gone through all the partitions and there are no common.pac files.
Or am I just the oddball out with a weird ISO?