I got it working today. Note you need to have the biz account for the VPS.

If you are running linux without the FP extensions you need to be on port 81. If you have front page enabled it will be just port 80.

Just follow the following format and it will work. Omnifocus should probably put a login / pass form on the webdav page or at least basic documentation on what url format to pass.

For Linux biz VPS without front page extensions enabled:

http://login:pass@yoururl.com:81

With FP enabled:

http://login:pass@yoururl.com

Been working well for me. Pretty slick and beats paying for more hosting then I already am.

Hope this helps.

Matt