goodinventor:
Hmmm...it looks like the best option would be to use a 3-pin female to female jumper wire.
I agree. It looks like a 3-pin female jumper should work. You'll just want to make sure you have the polarity correct since your jumpers won't have the orientation tabs on them.
goodinventor:
To answer your comment about limitations for programming, there is an Arduino library for it.
Yes there's an Arduino library for it. I don't see how this will help you connect sensors to the MeccaBrain.
goodinventor:
I also read the documentation they provide about the MeccaBrain and the smart modules. There is enough information that I can add a custom sensor to the MeccaBrain, provided that I have the proper connector to hook it up.
I don't see any information about connecting custom sensors. The only "sensors" it has are the position sensors in the servos. The MeccaBrain doesn't appear to do more than playback recorded sounds and motions. There isn't a way for the MeccaBrain to take actions based on any sort of sensor input.