You are not gonna have much luck, as LAPD is a digital system, which means that a 246T cannot receive and decode the signals. Much like the digital TV transition that is forthcoming, and the difference between analog and digital transmission, is the issue you have with your non-digital scanner (yes, the display is an LCD digital display, but that is not what a digital scanner is). Basically, you need a scanner which decodes digital transmissions, and unfortunately, that scanner won't do it.
When you look in the RR database, the signals you CANNOT listen to are listed with a "P25" in the "Mode" column. If the mode is NFM or AM or FM, you can monitor it, but as you can see, LAPD does not have many of those.
Sorry to break the bad news...