Hi:

The way I handled this is: 1) remove the core prerequisite
2) have vcredist.ext as a support file
3) do a check for the covual C++ redistribution (if installed set variable to 0, if not set it 1)
3) let your installer run as normal but right before the first file copy display a message saying something like “one or more required components were not found…” if the user clicks yes %_SB_RETURN% will be $IDYES$ if not it will be $IDNO$. If the user chooses yes, run VC++ install in quiet mode, if not, exit install.

Hope this helps :-)