Yes, what you describe is theoretically possible. By using the right gear ratio you can up the torque -- but you also reduce the speed, and the gears might get really, really big..
I assume you're trying to LIFT 1kg against gravity, which would mean you'd need 9.8N. But the lifting ability of your motor depends on the radius of the gears, so let's just play with torques (you can deal with the actual forces once you choose the radii of the gears):
If you have 40.5mN-m torque and you want 405mN-m, I need a gear that has ten times as many teeth (and is 10 then times larger). Just as a rough calculation, it seems that you'd need a 10:1 gear ratio (and that 405mN-m is about right to be safe), but as you can see this would require a 229mm gear! Also, your larger gear would be spinning 10 times slower than the smaller one, so if the smaller one is only going 1rpm, it'll take a LONG time to get that 1kg up there!
**EDIT: Screwed up my units, changed 22.9mm to 229mm.