i wouldnt remove the needles, i've fitted white dial kits to many cars and never had to remove a single needle.
getting them back to an accurate positon will be hard, once the needle is reomved there is a good change the pin will rotate. there are 2 types of needle, those that have their position kept using a small pin that the needle rests against (spring loaded needles, most commonly for speedo's), or those that are electrical and the position is relative to electrical input. the spring loaded needles will be almost impossible to get back in the right position because the pin rotates as son as the needle is removed, but the electrical ones should be less trouble, just make sure you use the igniton to reset the positon of the pin before sticking the needle back on.