Allan's RTP3 Clone heater CCS question

Hi All

I'm trying to learn EDA and build my own phono and I don't understand some things.

How to get 6V3 to the heater if the LM317 is set for current regulation.

What are pins 1, 2 & 3 for?

Regards
https://dl.dropboxusercontent.com/u/18574055/LM317.PNG

https://dl.dropboxusercontent.com/u/18574055/RTP3%20Heater%20CCS.PNG