It depends on why it does not display. Either your CRT takes tool long to lock into the signal or your video chip will not use the CRT until after the BIOS initializes.
If the CRT takes too long to sync try hitting the Pause key. You can then hit any other key to un-pause.
If it is the video chip then you are out of luck.
Tried your recommendation. Pause works ( I can see the dell screen stop with the flashlight) but the monitor fails to start until it gets to logon...then you can hear the monitor kick in