I believe the Panaracers are old-style tubulars with an innertube inside the casing just like a regular clincher except that the casing is sewn to itself instead of being wrapped around beads. You treat the innertube just like any other innertube. Gently. If you have damaged the tube-valve stem joint, just like any other inner tube, it is ruined and needs to be replaced. (Which can be done - you just cut all the stitching, remove the tube, place a new one in the casing and re-sew. Glue the rim strip down and the tire is ready to go. But I wouldn't advise trying this unless you are either a monk who needs to practice patience or a prison inmate with a lot of time to kill.)

So, lesson - be careful with those valve stems. you have far more to lose than with regular clinchers. (Oh, that sealant idea? The air has already left your tube. It will find it's way through the tire casing and the tire's rim strip. You are not going to stop it, no matter how big a mess you create. Now, if I am wrong and those Panaracers are tubeless. forget everything I just said.)

Edit: if the leak in the tube is not at the valve-stem, you are in luck. A regular patch will repair it just fine. The challenge will be finding where the hole is. The valve hole is the easiest escape for the air. The hole can be anywhere. Pump the tire up hard and place it under water. Hopefully you can see the air bubbling through the sidewall in one area. If it won't hold air, fill the tire continuously and run it by your ear and listen for the air.

Replaceable valve stems - BITD, valve stems weren't replaceable. We learned to be careful.

Ben