Hugin and Autopano-sift on a Mac

Hopefully someone can help with this somewhat obscure problem.

I've got a bunch of panos to stitch together and since I don't want to
spend the next week picking out control points, I thought I'd give
Autopano-SIFT a try. It seems to be working OK from the OS X Terminal
window, but every time I try to run it from within Hugin (v0.5, the
first "stable" version), it fails.

After mucking with the various shell scripts, it seems that the problem
seems to be that any sort of call to the MONO environment fails, even
just a simple call to /usr/bin/mono with no arguments. I get the same
behavior using either the script stored inside the Hugin bundle or the
autopano-complete.sh script that came with autopano-sift. I'm running
Mono 1.1.11, the most recent version for Mac.

Anyone ever seen this, and know a solution?

I can work around this by running autopano from the command line (or
picking the points manually), but it's sort of irritating that things
don't work the way they should.

Thanks for any hints that might be forthcoming.

-dms