ive recently been trying to get a lucky egg in my gen4 games as in:
but mostly soulsilver and platinum
in platinum I can never get mr backlot to say that there are chanseys
and I can never get a swarm of chansey or in a route where they are in soulsilver
All I can say is to continue your search and eventually one will show up. Although if you ever plan on getting either Pokemon Black or Pokemon White, I'd wait until then considering you wont be able to trade it over. Also, you get one for free!
Best of luck on your search!