[TYPO3-english] adding rel="nofollow" to the <a> tag for pages that are of type "link to external url"

[Simon Browning]

Is this doable?

I've seen a few methods to modify the link for a tags in the content, 
but can't find a way to add the rel="nofollow" for these page types in 
the menus.

Any tips/boots in the right direction would be most appreciated.

Thanks.

Simon