software estimation

I have a piece of code written to copy files, and a lot more, to a mainframe. I have to write another piece of code, from scratch, to do the same of actions to the same set to a UNIX box. I have to estimate how long it will take to write the second piece using the first piece as my starting block. Does anyone know of any methodologies which I can say, given x lines of code, it may take me n hours? The target language is PERL, but I could substitute C/C++ at a pinch.

>>13
Doesn't what you're saying contradict the results of most empirical experiments, who have found that LOC per hour per person tends to stay in the same order, even with vast difference in the expressiveness of the languages?