Some 1911s are easy to install the slide lock directly into the frame. Others require you to roll it upwards and down into the slot.
Here's a cheap and easy to make jig to reduce your chances of an "idiot" scratch.
Grab a piece of plastic like from bubble packaging etc. Line on straight side along the length of the edge of your grip.
Draw a reference line just under the detent/plunger notch for the slide lock.
Draw a circle around the mag release, as exact in size as possible.
Cut along the reference line for the top of the jig.
Cut the piece of plastic just longer past the mag release reference mark.
Use a hole punch and punch out the hole for the mag release button.
Stick a piece of masking tap on the underside of the jig. This will help prevent it from slipping around and losing it should it fall on the floor etc.
Your jig should look like this.
How to use the jig:
When you're ready to reinstall the slide lock, place the jig on your pistol with the mag release through the reference hole.
Line up the side of the jig with your gun's grip.
Insert the slide lock into position with it sitting on top of the jig.
Carefully slide the slide lock upwards and down into the notch.
Lift the jig up and away from the mag release end and remove it.
Press the slide lock into place. You are done.