I'll second tony's comment. I can save a button script as a compiled file (.mcc), but when I go back to "Edit Button Script" and click on the button, the original .m1s opens. What I'm trying to do is make it so that button code can not be messed with or even in human readable form...in other words, compiled code.
Edit...
Messing with this more, it appears that I can only save a script as an mcc file if I rename it. A button script always has the name HiddenScript, so when I try to save it as an mcc file, it just tells me that HiddenScript.m1s already exists and asks to overwrite. If I rename it to something like HiddenScript1.mcc, it saves as compiled code, but is not attached to the button.