The best thing to do is to overprint halftones over a solid, or to not use converging gradients in your design.
For instance: Sunburst gradient of yellow to red to black.
1. 100% yellow for the entire gradient
2. Overprint red gradient
3. Overprint black gradient
Results are not misregistration and a very nice blend.
Now if you are talking about CMYK or other type of halftones then you may want to look up the way to distance adjust foils. I have never done this so I can't help you there.