I haven't dealt with oak, but when I cut up some maple on the property last year, I just sawed it into pen blanks while it was still wet. A few distorted or cracked (mostly those cut through the pith in the center - which should've probably been discarded anyhow, but I was sloppy curious to see what would happen), but most came out just fine. They also dry much quicker that way.
If you're planning on doing segmenting or anything that requires perfectly square blanks, though, you'll probably want to cut them oversized, then trim once they're fully dry.
If you're trying to dry larger chunks, another alternative to paint/pentacryl (which I had mixed luck with - take this recommendation with a shaker of salt) is painting the ends with a mix of mineral spirits and paraffin canning wax. I use a little temperature-controlled deep fryer to keep anything from getting too hot, but if you're careful you might also be able to use a double boiler on an electric hotplate. Unless you live alone, don't use the kitchen - you're going to make a huge mess of it.
One other addition on the bowls (again, take with much salt - I've done this on a sum total of one bowl, and it ain't dry yet) is that a lot of people will pack them in the bag in their own wet shavings, supposedly to help them dry more gradually.