Much like doing a conversion to a 1/2 wire on a 10si alternator - this trick will work to run a mitsubishi 3 wire alternator on your build to give more power than the charging circuit can provide.
Almost the exact same method as Ryf (I think) described on the DIYgokarts forum and works the same way. Granted this is for the 3 terminal V-belt mitsubishi alternator. I don't have any good 10si but I had this, and knew it was internally regulated so I tried it. It worked. Note the mega fuse is optional - but it wouldn't hurt to have something there to protect the battery in case of surge.
Note the mega fuse, as previously stated is optional. This creates a self-exciting alternator that shuts down when the trigger (key or other switch) is turned off. Works a treat.