The simplest way is to install each of the Pre-Req's manually. The best place to search for these is download.microsoft.com. I'll refrain from posting links as these redistributable packages are always being updated.
The Visual C++ Redistributable Package presents us with a slightly different challenge. The package is unable to detect it's installed state so CRM always installs it. So we need to create a Redist folder, subfolders for i386/amd64, a VCRedist folder and then place the VC++ install files there. Your full folder structure should look like this:
- \Redist\i386\VCRedist\vcredist_x86.exe
- \Redist\i386\VCRedist\vcredist_x64.exe
- \Redist\amd64\VCRedist\vcredist_x64.exe
- \Server\i386\SetupServer.exe
- \Server\amd64\SetupServer.exe
- \Client\SetupClient.exe
- \DMWizard\SetupDMClient.exe
- \Exchange\i386\setupexchange.exe
- \Exchange\amd64\setupexchange.exe


