I've written a FoxPro adapter that is good enough to connect to a FoxPro database to fish out basic fields.
Currently all committed Cayenne adapters include support for reverse engineering and schema creation. I think that's overkill for MS Access and FoxPro. FoxPro and MS Access would only be used in applications for bug-by-bug compatibility with some existing application and not as a backend for Cayenne if the developer has any say in the matter.
Couldn't Cayenne support adapters of two types: full and simple? Simple being only basic read/write access?