My solution (it's not simple though):
IF it is REALLY many fields and really many possibilities of choosing then you can make a negative form that will write you the scripts.
(Then you just need to overgive the fieldname to a specific field into a scripted script.)
(Got a form with 190 checkboxes which handle about 2 600 if sentences... [hell didn't get they got that much] changing frequently ^^ you can imagine how long major changes take... ^^ about 1 min each ;D )
Though making a negative and a script that provides you with scripts for your original, it can be quite some work, especially in your case.
You'd at least need 1 larger script (for your scripting field) and one small script (this is standardized) you put into each field you want disabled.
Probably a third and a fourth script if you want to be able to change it in a simple way.
Another (simple) method would be to hide them instead of disabling them. You could wrap them into subforms then and work with these...