Well,
That is one of the fun things about the electric part of the hobby. You may want to repost this in the electric forum, most of the folks here don't fly much electric, but I can tell you it will most likely involve a collet adapter like this... http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5122&Product_Name=Propel ler_Adapter_(colet_type)_3mm
You should be able to find one at the LHS (Local Hobby Shop). The important thing to consider is the shaft diameter on the motor.
Good luck,
Curtis