Adapting music loops to my chord progressions

I compose melody and chord progressions, then develop arrangements in Jammer Pro, which I then export to Sonar to change some instruments and add vocals. I would like to be able to use some of the contemporary music loops which are available in Sonar or for purchase from various sample production companies. However, I don't want to use whatever chord progressions are used in the composition of the loops.....I want to use my own.

Obviously, drum loops are not a problem. For the multi-instrument loops, the claim is usually that they will adapt to your song's key and tempo, but nothing is said about chords.  For me, is the only way to chop up sections of the loop, change the key to what the chord is, and insert it at each chord change for the length of that chord change? Or is there an easier way; am I missing something? Thanks.