Add O2 to HDM Z1 Auto

[wyobob]

How, EXACTLY, should I add prescribed O2 to my HDM Z1 Auto output air?  And, will supplemental O2 add significantly to the pressure that is delivered to me?  My APAP settings are low:  4-6 cmH2O.  That is equal to 0.057-0.085psi.  I need this low pressure for proper therapy.  I am wondering if supplemental O2 will increase this pressure out of my range of tolerance.  My doctor prescribed 2 liters per minute of O2.  I have read that this results in pressures on the order of several psi - way higher than my therapy range.  If I install a one-way valve as instructed in such supplemental O2 setups, that will deliver all of the O2 pressure to me.  What will happen?

[Gideon]

It depends,  
Some masks have an attachment for an O2 hose.  
I searched amazon for "cpap o2 adapter" and found them for a 22 mm hose.