In October/November 1992, Possum Dixon played three shows at Jabberjaw (October 10, October 24, and November 3). The flyer for the gigs said that the November 3 show included Dos, Roger Manning, and Beck.
Possum Dixon was a pretty big band in LA through the '90s, lead by Rob Zabrecky (who plays on Mellow Gold). They shared many bills with Beck. Dos was Mike Watt and Kira Roessler's duo project. Roger Manning was the anti-folk NYC artist that Beck knew from his time in New York; not Beck's later keyboardist.
Interestingly, we also have a flyer for a show on the same night for Beck's band Loser and possibly Beck's band Skunkhead, at a different venue in LA up the road. This one started at 9pm; the Loser one at 11pm. So I'm inclined to think Beck was just busy that night.