I was trying to figure out some filling ideas and I heard about mousse. It sounds really delicious but I don't want to use pudding mix. Is there a way around it?

Well mousse doesn't have to be made from pudding mix...I actually wasn't aware about mousse made from pudding mix. Do you still have to refrigerate pudding mix mousse? I've always used mousse stabilized with gelatin or sugar syrup and egg yolks. Since these are really soft and fluffy you need to use a buttercream dam though. 

I've been looking through the gourmet flavors post and there was lots of people using pudding mix for a mousse. And the dam can be just regular buttercream, right? doesn't have to be extra stiff or anything? I would think that if you added dairy and eggs to the mix, it would have to be put in the fridge

Yes it can just be regular buttercream. Some people use extra stiff but I use regular IMBC or SMBC. & yes mousses with dairy & eggs need to be kept refrigerated until shortly before they need to be served so that the cake can have time to come to room temp. Not too long though.