just treat it as a normal switch, all it does is break the mains to it when you operate the test switch
if its maintained the e/l will have a sw/live connection which is where you would wire in with all other lighting, so the emergency light is lit up when a sw live is inputted to the uinit.
if its non maintained the light is not required to be illuminated unless the power fails to it.
eg.
6 amp mcb -----twin n earth------e/l test switch------main in to common, sw to e/l
operate switch it cuts power to fitting, reinatate and tube goes out (if non maintained) and charge light comes back on.
just treat it as a special light fitting with its own special switch, some peope designate them there own mcb and some people use the same power source that the ither lighting is on with.