To link from your product info page to the manufacturer's product sheet, all you have to do is add the URL in the product entry page (Catalog > Categories/Products > your cat > your product > click "e" button).
At the bottom of the page find this:
Products URL:
(without http://)
and enter URL.
Your product info page will have a line at the bottom like
"For more info see this products webpage" which will be a link to the product sheet.
Note - you can change the location, wording and style of this link if you want.



