Need help changing the modded snes ogg's to another ones.

I've been searching for information but I couldn't find any. basically I need help changing the ogg files from the snes soundtrack mod to an alternate soundtrack in the style of Mother 3 by Kase. I was trying to do it myself for a long time but there's a lot of problems like some tracks being slowed down and me being generally bad at audio mixing. Thanks for any help in advance.