I have 2 blog posts on my blog that might help you.
Splitting txt files:
mibuso.com/.../how-to-split-microsoft-dynamics-nav-object-files
Combining txt files:
mibuso.com/.../collection-individual-nav-object-text-files-in-one-file
I also show the file splitting in my latest video:
mibuso.com/.../prepare-team-foundation-service-for-microsoft-dynamics-nav-development
Hope this is help full
\Soren