Something like this is your best bet.
http://www.sunlightsupply.com/p-14497-ideal-air-dual-hose-portable-ac-12000-btu.aspx
Drill two 6 inch holes, in your wall or attic or whatever, pull some insulated ducting down through the one room, into your grow room, and hook up the two hoses to the two ducting hoses coming out of where ever.
The air flow from the other room operates the AC. It brings in cool air from the other room, runs it through your AC to cool it, and when it gets hot it sends it back up the other hose. So your effectively using the other room as a lung for your A/C. And the AC is cooling the air in your grow room without exhausting it outside. So if you are enriching your air with Co2, then your not exhausting it out the window with a window AC unit. It's all very efficient, but costs about $1 to run per day.
That or just cut a window out some dry wall, and frame it up for an AC unit. You could pay someone to do it, if you don't know how - I'm sure. Tell them you want a home office that has Air Conditioning. They will frame it up and install it for a price.
Good luck. IIRC, co2 isn't meant for 90+ temps. I keep mine around 82-84F. I think most people don't run temps above like 86-88F.
Also, your going to need a dehumidifier if your growing in a sealed environment. The moisture will have no where to go once transpiration occurs. You risk mold if you don't dehumidify.
Overall to do it right your looking at like $700-800 for ac and dehumid. And About $500ish for a simple regulated co2 setup ( like $200 for a monitor, $200 for a tank, $15 materials, $20 for a refill).