There are various converters in csound between midi and frequency, have a look at http://www.csounds.com/manual/html/midinoteoncps.html
Or
http://www.csounds.com/manual/html/cpsmidi.html
But in general, there would be no problem in passing a frequency as a parameter of the score.
I cannot look at the csd now (I am travelling with train) but if you could explain what kind of problem you have I’ll try to help if I can!