If you go in the XSI > Scripts > External Tools section on this site, you'll see at the bottom of the page a script called Maya Camera 1.0, or something like that. This exports the XSI camera to Maya, I tried it and it works fine.
For a compiled version of the dotXSI exporter for Maya, look on www.edharriss.com, plug-ins section.
Hope this helps
Salutations - Cheers
Bernard Lebel