RV uses 4 warble tones per octave, so I use 1/4 octave bands. A repeating logarithmic sine sweep is played thru the speakers, and digital bandpass filters are used to produce the band levels. Once you've set the right volume level, the software gives you the 25% target outline for adjusting each band properly.
You could probably do something like this with an off-the-shelf RTA (e.g. the one in REW), but you'd have to track the target levels yourself.
The program is written in Python, uses PyAudio to capture sound input, scipy for the bandpass filters, and wxpython for the GUI. This makes it reasonably portable. I've been meaning to clean up the code and put it up on GitHub.
I get excellent sounding results, and the EQ process is much faster when you can see the effect on all the bands at once. But being the author, I'm able to deal with the idiosyncrasies of my own design. It would take more work to make it generally usable.