To make it LOOK like running a script on data entry = yes.
To actually do it...what version are you on? FMP10 has script triggers that can do what you seek.
To fake it if you're on FMP9 or earlier, you can put an invisible button over the check box (lay the button over the box, choose no fill and no border) And have the button launch your script that does the following
Perform Script[check the fields]
Does that do what you're after?
Tha sounds like it might work. Would it be the same for Radion buttons? I have version 9, I purchased it on December 24. Ii am awaiting the upgrade to version 10.
I suppose that could work for radio buttons too, but you'd need one invisibutton to cover each radio selection. That way the setfield would set the right button. I haven't tried it for a radiobutton before, but I don't see why it wouldn't work.
If you're planning to upgrade soon anyway, you might find it worth waiting and using the triggers instead. Your call.