The only way that I know of is to use a laquer based primer- and I think it's just about obsolete. Besides, if you use it, you can't use base/clear or urethanes- the good stuff, because the laquer does bad things to it. (I'm not sure about enamel) Also, your paint job is only as good as that first coat of primer... just get the good stuff. You can get mixing cups for free when you get paint from the paint shop. (Usually) and you can mix small amounts at a time.
