decupage virgin...

[smoldering.livejournal.com]

So I'm working on an oil painting of japan for a friend of mine, and I wanted to try decupage (did I spell that right?) and put some black and white shots of godzilla and tokyo and temples in it. But I'm not sure if the decupage stuff is going to mess with the oil paint.
Can anyone toss up some advice?
I'm using winton brand paint if that makes any difference.