uhmm I'm a little skeptical about that mod you mention...
Remember that you're doing that voltage test without engine load...for that you'd have to be riding the bike!
It could possibly kill your battery by letting to much power to her overcharging....the reg/rectifier is designed to control that voltage.....
You could however, fit that cable you're talking about and adding some resistors that could keep the voltage on the exact amount that will let the battery be charged safely..
The safest way would be if you could weld a few cable terminals on those cables that will fit tightly onto the reg/rectifier contacts!
Use preferably some insulated cable terminals.. we don't want to have any sparks comming out from the rear of the bike besides from the exhaust
Did you understand what I was trying to say? If not, just tell me and I'll explain it better...