My main concern is whether dofollow is interpreted as more important than links without any
rel attribute. Does it make any difference for search engines?
What some people call a "dofollow" link is just a normal link - i.e. a link that does not have the
rel="nofollow" attribute. If you use
dofollow in the
rel attribute of a link, it is simply ignored by search engine spiders.
So, what you want is simply something like this:
There is no dofollow (or similar) attribute you can add to the link. The absence of
nofollow is what you're looking for.
Note: this answer was loosely based on this answer at Drupal Answers.