Most any place that sells off road buggy parts, or any place that has EMPI brand parts will have (or can get) wheel adaptors. They are avalible for a wide variaty of combinations and they aren't too expensive.
Lots of folks use them, but personally, I wouldn't. I've bought two bugs with 4 lug VW to 5 lug Chevy wheel adaptors on them . . . I pulled both sets off, replaced the wheels with stock steel VW wheels and gave away the adaptors. If you want to use a non-VW wheel, a better alternitive is to buy good German drums (or rotors) either already drilled for the Chevy pattern, or with no holes and have them drilled. Adaptors just add an unnecessary layer of potential problems.
Here's the EMPI online cataloge listing for their adaptors.
http://www.empius.com/w/wheelcaps.html#adapterSun Coast Bug (
http://www.Suncoastbug.com ) in Tampa, and Bug Stuff (Herb can give you their number, I don't think they have a web site) in Penn. are two vendors that handle EMPI parts and will treat you right if you tell them you are with the Volks Folks in Chattanooga. OK, Tony and Suncoast and Jack at Bug Stuff will treat you right no matter what . . . but tell them you're with the Volks Folks anyway. If you're not in a big hurry for them, let them know you what you want and they will bring it to a show here in the southeast and save you the shipping. As far as I know, they wil both be at our show in April.

You can probably get them here in town at Mainly Foreign . . . just forget that I said they weren't too expensive!