We have done a lot of work with BTO.  Unless the BTO items/categories were extremely predictable, I have a suspicion that a multi-column arrangement is going to be a real drag.  Others may have a different view, but that's my feedback.  I think it might be tough.  Do you have artwork showing how you feel this would appear once done?

 

Have a look at http://www.letterprinting.net/store/pc/1-sheet-letter-8-5x11-2p1.htm

 

In that case we used our "tabbed product page" feature, and merged the tabs fields into the middle column of configurePrd.asp.  (Our mod normally touches viewPrd.asp, the product detail page.)

 

Something like that, if your client was open to his description running down the middle, and the bto items on the right, might be much easier to pull off.  By squeezing the description (and perhaps other content) into the center, that's going to push it down the page a bit.  Then the BTO items would fit in next to it. 

 

Would that work at all?