sorry for not replying sooner.
any codecs available to acidrip will be the values that are returned if you ruin "mencoder -ovc help" that is where i find them from. if the codec you want is not there, then that is down to mencoder's configuration. lavc (FFMpeg libavcodec) is not a codec, but a package containing codecs. to encode to divx5 using lavc, you would chose lavc there and include the option "vcodec=mpeg4" in the options, it's there by default.