Is there any code in the tree already that would let me use these 
devices with XMame (for games that need more than two buttons, i.e. Xenophobe)?

---8<---
uhid0 at uhub1 port 1 configuration 1 interface 0
uhid0: Microsoft Microsoft SideWinder game controller, rev 1.00/0.99, addr 4, iclass 3/0
uhid1 at uhub1 port 2 configuration 1 interface 0
uhid1: Microsoft Microsoft SideWinder game controller, rev 1.00/0.99, addr 5, iclass 3/0
--->8---

If not, any pointers to specs? Any previous art?


Martin