For anyone else modifying the CCSslotMetal.il code, and wanting to debug easily as you modify the code, the first function tests the form's existence and brings up the form as it was last executed or modified by the user - NOT using the entry layer, or the default width value or default snap value.
Simply comment out the first "if" statement, leaving only the line :
form = CCScreateSlotMetalForm()
....prior to :
This will force the form to be created new with each call and you can immediately see your modifications to the form.