AppleShare only allows using local volumes for file sharing. It won't allow you to establish file sharing with a remote volume like NFS Share from InterCon. There's no public API to allow AppleShare to "publish" remote volumes mounted on the AppleShare server.
On a side note, it isn't that AppleShare 4.0.1 expects to see only HFS volumes. The volumes must be local to the server, they don't necessarily have to be HFS volumes.