Well this site has tutorials and such for rigging a model to get in-game:
As far as an exporter, there is a working version of an XSI Exporter that can be obtained like so:
The direct link for the export plugin is here:
(Download the bin file)
If that doesn't work you can go the long way:
Click on "dotXSI xchange for Max - Export" , then click on "dotXSI4max" (the name seemed a little deceiving to me, more like it was for max 4 and not 6 ). You'll want to download the "bin" file.
Another helpful tutorial can be found here:
MacD's Addendum To SpaceMonkey's Tutorial
This can help with a few areas that may seem vague as described in SpaceMonkey's tutorial. SpaceMonkey's tutorial is indispensable though, so I'd check it all out.
Here's the different releases from Raven:
NOTE: The Raven releases do not include an exporter for 3ds Max 6. You will have to get that as outlined above.
Hope all this helps.