Possible driver?

If you use a LM317(one of those mini one's with the 100mA current limit) with a 2500 ohm resistor, giving you 5mA, biasing a transistor with, let's say, a hFe of 100. that will give you a 500mA limit and then you can run a LPC-826 direct of 2 AA's, limiting the current to 500mA. Am I correct?

The main problem with this is that transistors vary widely in terms of actual current gain. While the datasheet may say 100 it could be much higher, o much lower.

Another thing is temperature. Transitors conduct more current the hotter they get.

It'd just easier, and safer to use an actual CC driver alone.