JUst asking, are you trying to make things harder on yourself?
As far as I know, there isn't but the install_gvsip is the most efficient method. All that does is creates a set of custom instructions and the custom outbound route you need in order for GoogleVoice to work. I wish is were as easy as 1 add outbound sip route with a regular SIP trunk and registration string, but it's not.
If you ran it once you have one GVSIProute called gvsip1, run it for a second number and you haave gvsip2 added.
If you insist on making is extremely difficult for yourself, read the ENTIRE thread called The Sky Is Falling...Really. That will get you so confused thatinstall_gvsip is now not such a big deal.
Happy reading (grabbing my excedrin bottle, oooh my head)
Genius, Why would I run the whole install script again when I just want to add a GV trunk?. I did this already on my main raspberrypi, I just forgot the command to run the script. I am trying to get this going on a second raspberrypi with a different GV numbers.