Unless I'm mistaken, the photos show what looks like it may be coolant. You could have a small coolant leak under the intake. I had a leak like that on my '93 and found that one of the intake bolts wasn't tight.
If the supercharger snout is leaking oil, it'll originate near the pulley and run down the snout towards the base of the supercharger. Using your finger (while the engine isn't running!), touch the underside of the snout just behind the pulley - if it'* leaking, your finger will have supercharger oil on it. The supercharger oil is clear but will probably have black engine dust in it. The oil seals on these superchargers seem to be prone to leaks. If you do decide to replace the seal, consider using a Viton seal rather than a nitrile rubber seal.
'99 Bonneville SLE, white, 112,000 miles
'02 Park Avenue Ultra, white diamond pearl, 88,000 miles