In a nutshell, here is what is involved.

A vacuum source is needed, like an old refrigerator compressor. A reservoir is needed to prevent the compressor from cycling too much. You will need an adjustable vacuum switch to accurately control the amount of vacuum to apply. The vacuum switch is what turns the compressor on and off. The wing is enclosed in a polyethylene bag that is completely sealed except for the vacuum line connection.

here are some web sites
http://www.deltronix.com/public/acp/acp-vbes.htm

http://www.pilotsguide.com/rc/vacbag.shtml

This was a much simplified explanation, as you will see when you visit these web sites.

Vince