Any method in which you supply a reasonable amount of ammonia should work. Fish-in cycling isn't ethical because there's a lot of potential for the fish to suffer painful ammonia burns, but it does technically work, you just shouldn't do it. Even if you didn't add any bacteria source, you'd get bacteria from the air.
If you don't get any live rock, I'd highly suggest getting some algae-covered frag plugs, rubble bits, and the like from an established, healthy tank. They'll bring over some helpful algae and bacteria. A handful of a well-established sandbed would also be good.
If you don't get any live rock, I'd highly suggest getting some algae-covered frag plugs, rubble bits, and the like from an established, healthy tank. They'll bring over some helpful algae and bacteria. A handful of a well-established sandbed would also be good.