Put them in water and add a drop of two of Hydrogen Peroxide. Give them some light and change the water every few days, adding the peroxide. I don't know how this works or why but it does. When you see the lentils swell (the little white knubbies you can either leave them in the water till actual roots form or you can pot them up. I have been reading on the Village GardenWeb that you can leave rooting cutting in the water all winter providing you change the water often. I've potted a bunch of mine up but there are still a few that are all rooted and I'm going to leave till spring, unless they start showing signs of decline.
Once you pot them give them good sunlight and watch them take off, Careful of spider mites and white flies. If they have keaves n the cuttings the bigger ones will turn yelllow and fall off. Oh well, they replace them quick enough. Do you have named ones or noids??