Since IS 2008 doesn't have Objects/Merge Modules available for these files, I included the vcredist_x86.exe in my installation, then I silently run it and delete the file during the OnEnd function, after everything else has been installed. The built in InstallShield dependency scanner indicates I need msvcr80.dll, msvcp80.dll, and MFC80.dll.
I have an InstallShield 2008 InstallScript project.