I just picked up a Dremel and router attachment last night. Got home and practiced a bit on some scrap depron. It's very easy, and doesn't take too long to do either.
A bit of advice - It's better to not cut enough away, than to cut away too much.
Here is a picture of some milling I did to a plane already put together. It's harder to do when the plane is already together... The next foamy I build I will mill out before assembling it.
(Sorry for the blurry pics)