If you have an enum contraption named "enum1" and a button intended for randomizing it, you could give the button a script something like the following:
on click do enum1.value:random["\n" split enum1.options] end
reading the "options" attribute of an enum contraption returns a newline-delimited string of options which can be cracked into a list of options with "split". Given a list, the random[] function will pick a random element, and the enum contraption also permits having its value written via the "value" attribute (automatically constraining writes to within the valid set of options).
If you're doing this sort of thing in many places, you could modify the enum prototype to expose a method for randomizing it, adding a function something like the following to the prototype script:
on get_randomize do on randomize do set_value[random["\n" split get_options[]]] end end
And then simplify the button script above to
on click do enum1.randomize[] end
Make sense?