Yesterday evening I did another test at home, this time booting the laptop I have there with Mac OSX Snow Leopard.
And using "Finder" to connect to a webdav server, I managed to connect to the demo site (6x), equivalent to the 5.x described in the documentation that can be found in WebDAV
or the equivalent but shorter:
(I don't remember if the trailing slash is needed, try with or without, if you have problems with the other)
WebDAV should reply asking you the password for that user "admin".
I'm not usre of the admin password of that demo site can be posted in some public forums (sorry, it's not in my server, so you'd better ask that passowrd on Irc, and you'll be given that pass in a private message, but not here)
Once there, I could browser the folders in finder from that tiki webdav file gallery tree.
But then, the same problem as I reported yesterday using GNU/Linux: files are there with some size, but they can't be opened by the corresponding Mac applications (which looks to me some issue with current Tiki 6 beta code)