Where in turbotax to list medical college room & board expenses ?

Room and board are not a qualified education expense.

If you are claiming room & board for a 529 plan distribution, you must enter the 1099-Q before your enter the 1098-T. Otherwise TT will not give you an entry point for room and board. Once you do that, to get the screen to enter Room & Board, answer yes when asked if you have book expenses, in the education expenses section. 

I omitted noting the expenses were intended to offset a 529 plan distribution ....

(If not offset, all/part of the distribution is taxable).

..

to list, see the dependent worksheet, part VIII qualified tuition program (section 529 plan)

Item 2, line h

then no taxes due on the 529 distribution