Most of the reading out there tells you about the trees in the wild, out in California. I had a hard time finding a good how-to out there for growing these trees from seeds on your own. Then I found Shoot's Blog, Growing giant sequoias in pots. In his post, he describes in pretty good detail how to germinate the seeds, grow them in cel-packs, and move them into pots as they get bigger.
It seemed doable, so I ordered seeds from two places, the first 15 from the Catalpa Tree Seed Company through LocalHarvest for $13. After doing some more shopping, I found these to be really expensive. I tried canceling the order, but was too late. Their customer service offered to refund the cost and said not to worry about shipping the seeds back. So, for customer service, they're great. In a few months I'll be able to see if they're worth the high cost, but in the meantime, I bought 100 seeds from the Whatcom Seed Company for about $7.
Following Shoot's Blog post, I first soaked the seeds in a glass of water overnight, then put them in a damp, unbleached coffee filter in a ziplock bag, and kept them in the dark. For my first batch, I left the seeds to sit on top of the water. In my next batch, I folded them up in a coffee filter, and made sure they were underwater all night, not just sitting on top like in the above photo.