Is there a way to launch NV with the 4GB enabler active? I get error code 51 after applying the patch.
Nope. Steam doesn't like people messing with the executables, so even if it's slightly modified in a way Steam doesn't like, it denies access.
The http://www.newvegasnexus.com/downloads/file.php?id=39964 is a great work around for it though.
Though I don't know if it still works with the new patch that was just released today. Probably not.Scratch that. It was updated recently, so it should work. Keyword being "should".