I want to create a script that allows me to zoom in to 125% rather than the standard 150. I am unable to edit the script step and wonder if anyone can give me some direction.

Nope, cannot do.

If you are trying to fit the layout to a new window size, forget it. The Zoom command wasn't really ever meant for this. It's only a relatively simple "magnifying glass" for browsing the screen better.

Support for multiple screen resolutions (or window sizes) *done right* means creating multiple version of the layouts, each optimised for the available real estate. Then you'll need to scripts to control navigation and work out which layout to display baased on the user's window or screen size.

And if you're thinking it's a big job, you're right. It also becomes a huge onerous maintenance chore down the track too. Encourage the clients to choose one window size by itemising the time and money you'll charge for multiple resolutions. Probably half the total cost of a job is in the interface: supporting two resolutions could add 50% onto the price easily.