Question Gimlet Gigglegibber to learn the location of the factory. You'll need 10 silver and to pull his arm like a lever. Take note of the pass code, Up Up Down Down Left Right Left Right.
The entrance to McScroogle Corp. HQ is a manhole cover a ways behind the Gnomeland Inn at -653,175,1086
Go down the tunnel to the gate. On the left is a lever. Click the switch ( 47,2,-36 ) to enter the pass code, and click it a second time to open the gate.
Just past the gate and off to the right is a crate of explosives. Click on it once to get the 12 Explosive Materials you'll need. ( 51,1,-20 )
Across the room to the south, on the western wall, is another lever. ( 52,1,15 ) This is the fire alarm. Use it. Come on, you know you have always wanted to...
The workers will all flee the factory. Security Bots will spawn, which are v and scale at or one level below you.
Avoid or kill as many of the sentries as you can, but you need to destroy all 12 of the work benches with the bombs. Three are downstairs right by the fire alarm around 40,1,26 . The rest are all around the upstairs.
NOTE: While it is possible to get the 12 desks you need by exiting the instance and restarting, McScroogle will not spawn so long as there are any desks remaining in the instance.
He appears on the platform on the middle of the ground floor, so if you did not clear the 2 security bots that were there you will most likely get adds. He has a couple of stun/mez attacks so it can be a difficult fight at lower levels. When you get him down to 0% he will deaggro and wait patiently for you to give him your demands.