I just read a great book about small-scale grazing by Gene Logsdon called "All Flesh is Grass." In it he talks a lot about his experiences with sowing different forages (including alfalfa) just by broadcasting the seed by hand (or with one of those people-powered
lawn seeders) right on top of the soil. No need for any heavy equipment at all. If you do have some animals on the
land, their traffic will help the seed get good soil contact. Even if you don't have any animals, if you spread the seed in the fall, the snow / freeze / thaw cycles (depending on your climate) will help work it down through whatever thatch is there to get soil contact.