Last year, the café was long closed by the time Masquerade started, even before the meetings. I worked as Masq assistant, and everything went fine.
We didn't have a lot of people signed up to host at the beginning of last year, but at the con, we recruited a lot of bored cosplayers to come and hang out with us. That's really what it turned into, a place where people (shy or open) could come and talk to someone friendly and just rest a bit.
Saturday you would probably be fine going from 11-4 or 5 PM, and Sunday is usually just 11-1, due to nobody really being there.
For those who do want to help out, but not run the thing, there's no set schedule - just come whenever you feel like coming to help out, and then leave when you have something else to do (or get bored). All you really have to do is say hi, invite people to come to the café, and make conversation with the 'guests'. We don't really have any 'performances' or 'special events' at all, although the Para Para group did do a routine or two on Sunday for the café guests.
For those who would want to run the thing, it would only entail making sure at least one person in charge is at the café to look over things for the entire time - we managed this last year by having 3 different people there, although I pretty much spent most of my time at the café when I wasn't prepping for Masq. You're also allowed into the Dealer's Hall before it opens to set up - all we did last year was bring in a CD player, some rose petals for decoration, and set up the single sign.
If someone's really willing to run it at least Saturday, I'll email the Mikomicon staff and see if we can't get some tables in there again. It shouldn't be a problem, but I worry that if it's not taken care of by this weekend, they won't have enough time to get it ready.
EDIT: Found an old picture from last year's Café: http://www.cosplay.com/photo/1734991/