You can use either the WScript or CScript executables to run a VBScript file using RunProgram. The only difference is that WScript will show errors in a MessageBox, whereas CScript writes the error to the console/stdout.
Here is an example using CScript.
rp = RunProgram( Executable( "CSCRIPT.EXE" ), Options( "\!"C:\runMe.vbs\!"" ), Read Function( "text" ) );
Justin