Do you mean on the stator cover? Or Hydralic clutch cover? It may be as simple as a 5 dollar gasket. If it's the stator cover you are set, let the engine grow cold so that the oil is nice and thick then put the bike on the centre stand and take off the stator cover. Be carefull as a little oil will drain out so its best to put a 1 dollar aluminum foil tray underneath to catch any drips of oil. Change gasket and retorque cover back on there and your set. I had to replace a bunch of stator cover gasket in my days. REMEMBER put it on the centre stand, if it's on the kick stand gravity will let oil continuosly leak from your crankcase. If you're fast enough you only lose about 300ml and it should take only about 5 minutes to be carefull not to rip the new gasket. Scrape any of the old gasket off there.
Do you leave it on the kick stand? A good way to test if it's the stator cover gasket is leave it on the centre stand one night and see if you get the same kind of leakage. The stator doesn't really have oil journals under pressure but it's designed to have a bit of oil circulate there to keep things from rusting and getting too hot. Since there is only oil usually dribbling in there and not under any high pressure, putting it on the centre stand would relieve any excess pressure from gravity and hence have less of a mess in the morning. It doesn't sound too serious, just a gasket to me.
I wouldn't drive too far with that, if only under gravity you're losing that much oil, imagine under pressure!!! If this is your only vehicle you can temporarily retorque the bolts on the stator cover to get a new gasket but that's as far as I'd drive with that much leakage.
Here is a pic I've found of a 98 B12 with belly pan:
Which is leaking Number 1 (stator cover) Or Number 2 (Hydralic clutch cover)?
From your description it sound like number 1 the stator cover in which case you're in luck friend as it's the easiest of the two to fix. Go grab that gasket!!!! I would use a T-Handle hex wrench on those allen bolts though, don't use a crappy allen key set. I believe it's a 5mm bolt. YOu don't want to strip those bolts!