You don't, really. It's pure luxury. I've got some Victorian/steampunk suits where it'll look very nice on my avatar. The fact that it opens and keeps
SL time is superfluous.
Although ... I guess you could: attach one on the spine or stomach, attach one to your hand. When you run a command to "check the time", an animation triggers, the one on your spine/stomach goes invisible, the one in your hand appears, the face opens...
Hmm. That'd be fun.