Jeff,
If the house paint is latex, try a latex specific paint remover like
Goof-Off. The active ingredient is Xylene, so it might be more economical to
buy it by the quart for a big job. Use non-latex rubber gloves in a very
well ventilated area...and of course test an inconspicuous spot to make sure
the original paint is non-reactive. I've had very good luck on bicycles,
antiques, etc...
Good Luck,
Ed Kasper
Detroit MI