I guess the only way to convert an .uif for the Mac is using a Windoze Software like MagicISO; see:
http://forums.appleinsider.com/showthread.php?t=75859
I renamed the .uif to .iso but the image was not recognized.
I am buying a new Mac today and will run MagicISO using Bootcamp. If the file you try to convert is not over 500 MB you could upload it to my .mac account and I will try to convert it for you.