It doesn't work like that. Instaspin is a PROGRAM that runs on a C2000 DSP that is designed to run it. It's not some stand alone chip that you can wire a bunch of parts up to and have it work. There is no throttle input unless you create one. In order to do that you have to write code for the C2000. If you can write an I2C or CAN communication routines then you can take an extra 5 mins and add the lines of code to do the A/D and read a hall throttle. If you understand coding in C++, adding a throttle is easy. I however had to learn about C++ (It had been 15yrs) and read up on the parts of Instaspin and do the tutorials so adding a throttle took me a while to get to.
I'm not sure if you understand what Instapin is or isn't at this point, but I'd like to hear more on the throught process before I say more. What feature does the arduino have that the $17 Texas Instruments F28027 Launchpad with Instaspin couldn't do?