Signed to Unsigned

Easy question to answer (I think) but I just can't seem to locate an answer on my own. I need to add the value of two signed numbers (e.g., -100 + 100) as though they were both unsigned. Is there a function that allows me to convert a signed number into an unsigned one, or to otherwise accomplish this?

Thanks!

P.S. I should note, I'm trying to do this in TorqueScript--not in the source code.