I was thinking a bit more about it and maybe the cancoth field could be set to allow more input. If it could be set so that 0 disables coth for the entire zone, and 1 enables it for the entire zone, and then have another option of setting which could be option 2,x,y,z,xr,yr,zr. If this option 2 could then have more information included with it, maybe you could set this up as a proximity to define areas.
It could pull the values from a comma separated input something like:
Code:
cancoth
2,0,0,0,50,50,25
Where, the first 2 is what tells the code that it is going to use the additional input that follows. Then, the 3 0s are the location of the center of the proximity you are setting. Then, the first 50 is for setting the X axis range of the proximity check. The next 50 is for setting the Y axis range, and the 25 sets the Z axis range.
I think the code I have posted here would do part of what is needed to get this set, but you would have to change the input type in the field to accept the additional input. There would also have to be some code added that will allow you to define the proximity. Maybe looking into the code for setting quest proximities would help to figure out what needs to be added to get it working to do this.