You can definitely use a neutral yeast like Bytor suggested. It'll still be a tasty beer, but it won't be a pilsner. If you can't ferment cold and then lager, you'd lose the crispness of a pilsner and the other lager qualities. It'll be fruitier and have more flavor to it than using a lager yeast. If that's ok, then you can use an ale yeast. I'd still try to ferment it less than 65 degrees, though.
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