[Andrew]

An alias isn't going to work because Apache doesn't understand aliases. It does understand symlinks (similar to aliases but with some subtly-different design goals).

Symlinks are created from the command line in Terminal like this: "ln -s <source> <destination>". For example (depending on your configuration): "ln -s /Users/jputnam/webdav /Library/WebServer/Documents/webdav/jputnam" - that would create the file "/Library/WebServer/Documents/webdav/jputnam" that is a symlink to "/Users/jputnam/webdav". (Make sure that the latter already exists. And is a folder.)

However, I suspect that security issues are going to keep that from working - apache probably isn't going to want to vend stuff from outside its documents folder that readily. And/or ownership and permissions on the folder that you link to will probably need to match certain expectations. I'm guessing that you will need to do some apache configuration to accomplish what you're trying to. But I'm far from an apache expert and I could be wrong.