Two most important parameters in the XF86Config file, ones that are crucial to the mouse working properly are the Protocol and Device.
As far as Protocol is concerned, it seems that gpm uses compatible protocol names, so please look there for the detailed information. Here is the excerpt taken from the gpm info page (just the few most commont types):
Table 1. Most Common Mouse Protocols in X
|Standard Microsoft mice.
|This is the standard protocol for three-button serial devices.
|Title says it all. This mouse decoder accepts standard serial options, although they should not be needed.
|This is the protocol used by old serial Logitech mice.
|Some bus devices use this protocol, including those produced by Logitech.
|The protocol used by most busmice.
|"IntelliMouse" on the ps/2 port. Also works with USB mice