Irrlicht Engine

I need to be able to access a few predetermined variables, perform basic looping, if/then stuff, and math while my game is already running. How is the best way of going about this? Can I set up Lua or another scripting language with out much trouble to do this or do I have to make my own mini-scripting language?

try out gamemonkey, it seems to be perfect for you:
http://www.somedude.net/gamemonkey
and if u need help have a look at these pages:
http://www.gamedev.net/reference/progra ... gmscript1/
http://www.gamedev.net/reference/progra ... gmscript2/

If you want to go the Lua route instead of GameMonkey, get tolua++. It makes integrating Lua extremely easy. But, the documentation for it is a little difficult to understand.