Are they still the same thickness as a whole pork loin, just cut into shorter pieces? Do you normally do whole pork loins, and just happen to have some that are cut into shorter pieces?
If so I would do them pretty similar to how you do a whole pork loin, from my experience, and what I've read here, it is more about the dimensions of the meat (width/thickness) than total weight. So a 6-8" long pork loin shouldn't really cook a lot different than a whole 16" long pork loin if they are similar diameter.
Having smaller pieces will allow you to stagger them a little too. If you have some that are noticeably thinner/smaller diameter, you could throw them on a little after the thicker pieces to try and get them done at a similar time. Shorter pieces may get done a little quicker than a whole loin, but I don't think it would be anything significant.