TAGS in Pyris 1

Is it possible to have lets say two gases connected to the TAGS in Pyris one (let's say N2 and O2) and make a mixture of them?

For example if I wanted to put 79% N2 and 21% O2 with only the two gases connected to the TAGS

 

Is it possible and how would it be done?

I was reassured several times it can be done, I just don't see how.

Thank you for your time.