I don't follow his plan, but my wife went through the class at church, and I occasionally listen to him on the radio. My impression is that the steps are supposed to be done sequentially, not simultaneously. He'd probably advise you to complete step 4, then complete step 5, then complete step 6.
In your example, after step 4 is complete, if you're working on step 5 and have some extra money that you'd like to put toward step 6, you should instead put that money toward step 5. Paying off the house is something you can do eventually, but that college money needs to be there first.
I'm more familiar with the "getting out of debt" steps of his plan, so I may not be 100% right here.