CC2640R2F: DIO configuration with IOCFG

Hello, 

I am working on pin assignment with cc2640.

I want to use dio configuration, ICCFG, but can't understand how to do.

Could you give me a guide?

For example, if I want to configure pin 21 as AUX IO, I have to assign register as 8h.

is this right? then which file should I working on?

I kept looking on example project, but couldn't find where each pin was configured.

I attached the document that I am looking. 

Thank you.