Well, you have a couple of options in addition to Vintage. The first is to look at the Volunteer page here:
https://www.eaa.org/eaa/support-eaa...ture/available-airventure-volunteer-positions
Second is to simply ask a volunteer doing the job you might want to try. They’ll be able to get you contact with whomever is the chair for that volunteer area.
If you are an EAA member you can also try posting your request in the EAA Forum’s AirVenture sub-forum. IIRC, that’s basically how I got into the area I volunteer with (if wasn’t there it was over on VAF).
Finally there used to be a bulletin board over by the Red Barn, more or less across from the Fly-Market entrance, that Chairs would solicit for volunteers but I’m not sure it’s still there.