Switching on the dust collector is a very common issue with woodworkers. All
you need is a radio controlled relay for the vacuum. It is called a "Long
Ranger" and is intended specifically for this purpose. Here is one place that
sells them, any good woodworking store carries them (Rockler, Woodcraft, etc)

http://www.pennstateind.com/Merchant...egory_Code=LRS

Dennis