I don't believe we can actually put class reqs on books. I believe they are supposed to be tradabel as well (the first 2 levels at least, like other tomes) but thats bugged atm. They are supposed to have a similar translation process. Expect the class tomes you are using to becoming tradeable and unusable after we work out the bug. Your exp will of course be safe.
I'll check the pre-reqs out today, and make sure they are all working properly.