Yes, you can do that. I know Yahoo has some rules in affiliate marketing, you ought to have a landing page instead of send them direct to click bank. Yahoo are very slow in approving your ads
on a side note - their keyword tool is also a bit slow, as for each keyword it'll automatically set your bid to the #1 spot, which sometimes can be a $5 or more, etc -- ridiculous price. so you manually have to go through your list and lower the bids - one by one, for each keyword. the solution is to create a category first, turn it off, then add keywords to it. after your keywords are approved set the max CPC for the category, turn the category on, and you're good.