I don't know if you mean the fretboard, the back, or both, but here's what I have.
I have a 1 piece maple neck, with the skunk stripe.
I used the birchwood casey wax ontop of the tru-oil, and while I liked it at first, I found myself using 0000 steel wool to buff up the back of the neck, more than likely scraping a good portion of the wax off.
I didn't put ANY wax on the fretboard, and I only put enough Tru-oil on it so there wasn't a noticible difference in color between the front and the back.
I'm guessing if you're using Tru-Oil, you wanted a "woody" feel to the neck. If that's the case, skip the wax.