I got this working on the command line ... but in my script it's still not working

I'm not positive, but I'd say the shell is eating one pair of backslashes. Basically, the shell sees \\\\, passes it in to perl as \\, which gets passed into the RE engine as \. Welcome to the backwhack hell that is multiple layers of interpolation. :)

So, in summary, \\\\ on the shell should be \\ in your script.