Mike,
The alternate function in Visual Pinball System is only to load Visual Pinball.executables. (VPinballX, VPinball995,VPinball99_PhysMod5_Updated). And you tested this function with PincabView and it didn't work. This was discussed in the post "Banzai Run - PinCabViewVPX_Launcher.exe" and you replied:
But it doesn't launch the PincabViewer_launcher at all
Running the line from command line, it is working fine
So thik Alternate exe is not working fine for this