I want to file 4868, but don't want to pay the tax due at this time. How do I get line 7 to show $0? Right now it shows I am going to pay the balance due.

[itonewbie]

What you're looking for is under Payments, Penalties & Extensions > Extensions (4869, 2350).  On the Federal tab, under the Automatic Extension (4868) section, on the line for Form 4868 payment (defaults to amount due) [Override], enter -1.  Yes, -1.  That's 0 in Lacerte-speak and that's the only language PTO understands.