sony visca rs-232 control for sony evi-d30 ptz camera


to any out there that may have the knowledge, i submit to you the following queries:
1. how can i gain serial control via usb ? i can't find a rs-232 driver that actually wants to show up in my system.(i have a sony EVI-D30L PTZ camera that has a adb style (round) 9-pin I/O, w/ s-video out (i have a usb adapter: a single piece usb b to serial (db9) w/the "Prolific" chip-set, their site states they have osx support, but i can't find anything but os9)
2. does any one know a source for a mac based control/driver for the sony visca protocol? or a way to gain control of an external ptz camera via a usb to serial port?

i'm running osx 10.4.2 on a 1.5 ghz, g4 powerbook, with 2 gb ram

anything that anyone can offer is greatly appreciated,