Wide angle attachment for Ang. 6-90mm?

[Daniel McKay]

Anybody have any advice for getting a wide angle converter to fit my 72mm thread Angenieux 6-90mm? Will the UWIII attachment vignette badly if I use 1 step up ring from 62-72mm? Perhaps the Canon C-8 version will work better as I believe it is a 67mm thread.
I'm also curious about the quality of the video lense attachments, such as those for the XL-1, but I believe that they won't work at all for S-8, true?
How about this guy:
[/url]http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... egory=4691[/url]
Thanks for your help!