Not being a woman, I can't help you with everything involved. HOWEVER, a while back, a friend and his dominant wife wanted to do just this.
What they did, which they considered similar, was to obtain a buttplug with a hole through the center. They made certain that the hole in the bottom could be covered and that it was made out of steel (theirs), but it could be made out of any material that does not expand drastically when frozen. He's always been forced to wear panties, so that was not a problem.
What they do is fill up the plug with red kool-aid and leave it in the freezer until she decides to give him his period. (It is a regular thing, so she does it once a month for X days.) While he's on the "period," he'll wear pads placed up the back of his panties (or diapers if she's feeling really cruel), and he's supposed to take the plug to work (or wherever he'll be at lunch) in his lunch box. At lunch he puts the plug in and wears it for the rest of the day. He is not allowed to take it out, she is the only one allowed to do that. Although, if the pad is "fully used" before he gets home he's allowed to change pads.
I'm not sure on the full mechanics of everything, but I could easily ask if you're interested in finding out more about that method.