How do I hook skidding tongs to this?

One of these! :)

http://www.tractorbynet.com/forums/b...ast-hitch.html

If your hitch is just like the photo. it looks like you can unbolt the top link "hook" and find a 12" pc. of chain to use with your tongs. This might be handy giving you some adjustment. A few good "whacks" on a chain link stood on end and held with some vise grips or something, will oval the link enough so that you can get a decent sized bolt through it.