Here is a very quick reference that may assist:
http://www.stewmac.com/tsarchive/ts0124.html
I was sure that Dan Erlewine posted a video or Trade Secrets item on the StewMac site in the last few months describing how he finished a tele with a blonde finish but I can't find it. My recollection is that Fender used to apply a white semi-transparent coat over the sealer coats then spray clear with a bit of tint to get whatever level of off-white is desired then clear.
I haven't tried this but you could mix some white pigment powder with the lacquer or sanding sealer and apply as a base coat. I got some from and artists supply shop - they had a range of colours. By being careful with how much you add you should be able to dial in as much or as little opacity as you want. Then clear coat with lacquer.
I have Dan Erlewine's guitar finishing book at home - I'll see if I can some more clues there and post another reply.
Andrew