Instead of using wire or magnets, just take small strips of 0.030 sheet styrene, set the part in place and glue the strip to the outside of the body part that is being joined staying away from sharp radiuses and it's done. Finish glueing the part in place and sand the strips off. Seems like a lot of work using the wire method.
If the part is cut correctly, you won't need any of this stuff anyway. Better results.