You can get perlite in the garden section at Walmart. I think they carry Shultz brand. Here is a link of what your looking for:
Schultz :: Perlite - 20258
Promix is just a peat based potting soil. A lot of people like it and I've had good success with it. Here is a link to Premier's distributors for promix:
Premier Horticulture – PRO-MIX growing mixes & Peat Moss: The ultimate growing performance
If I were to try it right now I'd soak the seeds for at least 3 days in water. I just run warm (not over 130) water in a small bowl or glass and change it every day. Then I'd use a deli container like Tog uses. For some reason I think the clear tops to let light in may make a difference. Or use a container and use saran wrap over the top to keep the humidity up. I would use straight moist potting soil. The old tried and true method is to squeeze it in your hand to where only a few drops come out (personally I make it just a bit wetter). Then just float it in the aquarium at 85 degrees or put it on a heat mat at between 75 to 90. Then don't be digging in there to see what's happening. Just watch it and wait till you see sprouts. There are great guides in the germination section. Ensete is just a little different in that you don't have to fluctuate the temps like Musa.