I have built a website using css and a blueprint grid platform. Can't seem to get my blueprint into
coffeecup. Does one preclude the other?

I'm not very familiar with the blueprint grid css layouts, but my guess is that if you by 'coffeecup' mean the html Editor (there are about 30 odd CoffeeCup programmes), you should be able to enter a reference to any sort of css file.

Anyway, I guess you just have to put into the Editor whatever divs and classes you have in your css file and fill them with content.