Yep,you are o.k.posting on this board because it is a general guinea pig question.
Yes,it is possible to potty train a gp.,but it is not easy,and is really only viable if you just have one ,or maybe two,free rangers.It will take a lot of patience and quite honestly,most folk just give up.Piggies are messy anyway as they trail hay all over the floor,and this sticks to your feet and gets all over the house.At least it does in my house!.I must admit I have never tried house training because I have too many piggies.
Do have a go though,you might succeed. Some pigs will poop in one corner of the pen/sleeping box,so you could try putting some kind of litter tray there.
Let us know how you get on. Mary