Interesting question! I've never personally worked with EL wire but this article mentions it isn't easily dimmed. The wire needs a high frequency (100V 2kHz) supply to be driven - what are you currently using to drive it?
Probably your best bet would be a dedicated driver with DMX input like the ones here.
While not your exact same scenario, I have used some 12v EL Ultra-Bright Wire (about 6' of it) a RC4 wireless dimmer. I had to write a custom profile to prevent some flickering when dimming, but it has worked for me perfectly for 6 months. Only issue I have is the power supply makes a small high pitched whine, but not noticeable from more than a few feet away. I know thats 12v and your looking for 120v, but my 2cents.
