I have a svcd mpeg-2 file on my computer, but I don't have all the other directories that are on the cd versions. Is there any program that can create the .dat and other files that I need?
Assuming your mpeg file is svcd compliant, you can just load it into nero (even easier using nero express) and let it do the job for you.
A DAT file is on a VCD (MPEG 1) only, on a SVCD its there as an MPG . As philamber said, just use Nero and select the Super VCD option. Load in the MPG and it will burn the disk for you automatically adding in all the other folders/files as needed.