I should have checked this before posting, id-tags don't work on td or th -cells.Added new custom HTML tag !!!Current!!!. This will have the value "id=current" when the program being displayed is currently on air, and will be null when it is not. This will allow the css to change the currently showing program.
EDIT (again)-> it works after all, I'm pretty new to CSS so I didn't know I could call #prog #current{} when #prog{} was ruling over #current{}. So Kev, nevermind that changing to classes