I personally use the injectable ivermectin - it's marketed for pigs I believe. I bought it at a local feed store. It cost me about $35 but it was enough medicine to dose thousands of pigs!!! It only takes a little behind each ear.
You need an accurate weight for your piggies and a proper syringe to dose it correctly. You have to be very careful not to overdose. You need to do the treatment at least 3-4 times about a week apart. Really bad cases can take more treatments. You need a syringe with a needle to be able to pull the ivermectin out of the bottle, but then you remove the needle when dosing it.
Guinea Lynx :: Ivermectin Topical Treatment Guinea Lynx :: Topic - I cannot believe I missed this
If you really want to dose orally, I can't give you any advice on that since I've never done it, but here is a link:
Guinea Lynx :: Ivermectin Oral Treatment
Whatever you end up using, make sure that ivermectin is the ONLY medicine in there. Also, if you are in any doubt as to how much to give, make sure to see your vet for help.
Good luck!