You need not condition kegged beer at room temp if you're going to carb with CO2.
If you do the 2 weeks at service pressure (10-12psi) method and don't worry about rushing it, it will condition just fine at the cooler temp (38-40*F) during that period. Get a small taste sample every few days and you'll see what I mean.
If it still tastes "green" after 2-3 weeks, you ought to take a look at your brewing protocols, particularly pitch/ferment temps and whether you pitched a sufficient amount of yeast.
Good Temp Control -----> Happy Yeast ------> Tasty Brew