Tough question here;

 

First an easy one to get warmed up though... Would there be any benefit to mummification from exposing the body to a CO2 enviroment while it's being dried? I'm confident there would be in theory but how about in the real world where most of rotting is being caused by aneroebic bacteria?

 

If a mummy were produced using such a technique would there be a means to detect it after 4700 years?

 

 

Perhaps I'm being dense here and there would be no advantage other than preventing insects and rodents from attacking the body while it's drying. I suppose there would be no changes caused by such a process would be detectible with modern instruments and knowledge. Perhaps it could be possible to autopsy mites and the like to see if any died of CO2 suffocation.

Generally the absence of oxygen would be beneficial (simple N2 would have the same effect) as anaerobic degradation is slower. Similarly drying at low temperature would be preferable. However, the key element is drying, as sufficient humidity would still allow for bacteria and other microorganisms to do their work.