Scott
Your first step should probably be some exploratory data analysis,
starting with some plots. How do you see the runtimes increase with
the number of lines of code, for instance? Is there an apparent linear
or nonlinear relationship? Same for other relationships. Then you
should formulate a theoretical model, something like
runtime = f(attribute_1, attribute_2,...,attribute_N) + error
In all likelihood your first model will be linear
runtime = a_0 + a_1*attribute_1 +a_2*attribute_2 +...+ a_N*attribute_N
+ error
You estimate the coefficients using a regression package and... Bob's
your uncle. Details about this ought to be in pretty much any
introductory stats book.
Cheers