Limiting the minimum percentage of oxygen in atmosphere maintained by an oxygen absorber / scavenger?
Oxygen absorbers have the purpose to prevent food spoilage by oxidation (of fatty acids, flavors, etc.), so the desire is to remove oxygen as much as possible and also to bind small amounts which may diffuse into the package upon storage.

In order to achieve a certain defined oxygen containing atmosphere, consider flooding the package with an artificial gas mixture, e.g. 5% oxygen, 95% nitrogen. Should be easy to obtain from scuba dive shops who are filling bottles with homemade nitrox blends if they are willing to give you a custom mixture (which in this case is not suitable for diving). 

Or just mix air and nitrogen or carbon dioxide (from a soda machine) by adjusting the flow.