From what I read it looks like RVD will have the same kind of contract that Jericho does. He'll show up for a little while and then disappear for a bit throughout the length of the deal. I'm guessing by being a part timer he will be able to dodge the drug testing much easier.
For those that haven't seen him in a while don't get your hopes up too high for his return. The RVD of today is not even anywhere close to the performer you remember when he left the WWE. I really do hope he's got it together and is in shape for one last memorable run. Maybe being back on the big stage will motivate him more.