I asked a similar question a while ago about Co2s and that thread should still be there and may help somewhat. I found that for pre-dilution the best thing for most of these CO2s is Isopropyl Miritstate (IPM) which then mixes nicely with alcohol anyway and has nice skin properties, plus make retard the evaporation of top notes a bit too (the exception was oakmoss, where it would not mix with the IPM). But generally, I now have simply learned to treat the Co2s like a concrete, put them in the alcohol perfume formulation, break up (the IPM does this in advance) and macerate (as long as you can, months is better I am told). You are then essentially making an alcohol "extract" out of your co2 "concrete", and getting a very nice, very complete scent out of it to boot. Then freeze and filter your whole creation as you would anyway, don't worry about the waxes that filter out. Of course ambrette may be different and I do not have co2 ambrette, and thus it would be great if you report back your experience.