You definitely would need to set the globals in a master script to ensure that all parts will read the values.
Some care needs to be taken with the globals though. If you have library parts that use them to pass parameters (hard to know this) they could reset the values you are depending on.
I once tried using a global to get my doors and windows to look properly for a reflected ceiling plan. Unfortunately I had to reload the libraries each time I reset the parameter to get the values to update globally, which pretty much defeated my purpose. I don't know if this is still true. If you try it you should keep this in mind.
All in all, the potential pitfalls may make this unworkable for you. You will probably find yourself spending more time fooling around with it than you can save in modeling time, and after spending the time you may still find that it doesn't work well enough to be useful.
Especially since you are past deadline, you should probably not attempt this unless the modeling time is crippling your progress. There are other tricks to saving time. Use the marquee to limit the model to your immediate work area. Turn off 3D fills in working section/elevations. Update your finished elevation drawing in a batch while you do something else.
Good luck. I hope this is helpful.
