Try looking on the "Porn Star" board here on TER.

Try looking on the "Ads Board" for Washington DC here on TER.

Try looking at Eros since some advertise there.

Try doing a search for porn stars.

Contact a porn star you wish to see directly (most have websites to contact them through if nothing else).

Lastly, I know there are "services", similar to an agency, that schedule porn stars who "tour". My memory of the names of these places escapes me right now but maybe some other gents would be kind enough to help you out (and refresh my memory at the same time).