I'm going to assume you are bottle conditioning, since this would be be pretty easy to do with kegs. I say this drinking a 3 week old schwarzbier which is delicious.
A bottle conditioned lager is a challenge, but can be done. A bottle conditioned lager-like beer is probably a bit easier.
I got a pilsner into the final round of a comp with 5 weeks, and it was good drinking at 4 weeks.
Stick with around 1.050 gravity - go too big and it might need some more time.
Give it a really good pitch of healthy yeast, aerate like mad with a drill and beater attachment if you don't have O2.
Ferment at 50f for 3 days then start raising the temperature, up to low 60s over the next few days, dryhopping about here if you need to. Once that krauesen drops and you hit FG, slam the freeser down to just above freezing (34f or so), hit it with gelatin and give it a few more days to clear. This is all happening in primary.
After about 10 days in primary, bottle it. Setup a temp controlled environment for your bottles - I use a cooler bin with an aquarium heater at 80ish. The bottles will carb up nicely within 10-12 days and you still have at least a week to get them in the fridge to clear up some more.
Good luck.