They do (or at least used to) offer commuter parking passes, however you'll most likely have to pay. I don't know how things have changed now that they have moved to a "secure" employee lot (as opposed the old one that anybody could drive into). IIRC, it was about $200/year for non-domiciled employees to park.

You might also try working out a deal with some of the local hotels to utilize their shuttle. The Fairfield, Hampton and the Holiday Inns north of the airport off of Route 28 may be able to accomodate you.