I bought a Puralator P239 filter/gasket for a th350 trans. The gasket comes folded and rolled up in a small box. Any tips on how to get the gasket to lay flat so i can line up the holes and bolt it on. I think this is a bad idea folding and rolling gaskets like this. The gasket material appears to be black rubber. Thanks.

Use a gasket adhesive. Loctite makes one that's red coloured and comes in a spray can. Spray one side of the gasket and stick it to the pan. That way if you have to take off the pan the gasket will stay stuck to it for easy reinstallation. I use this stuff everywhere, it works especially well on valve cover gaskets. You could also use yellow weatherstrip adhesive, but it's messier and harder to apply properly.

Last one I did I laid out flat on my bench and put a couple of big books on it for a day. Then it stayed flat and in position on the pan when reinstalling.

I like gasket sealer. I use the Permatex Aircraft or Permatex 300 (the former is stickier). It comes in a can with a brush in the lid. Brush it on the pan, set the gasket, and use the bolts the "wrong way" in the holes to weight it down against the pan until the sealer sets up.