For the EP45-DS3L I swear by DSDT (Koalala's ACPI Patcher - Selecting Realtek ALC888-0, and checking HDEF box) then adding one of these attached LegacyHDA's, from tmongkol's thread, in to /E/E. Easy as that
This was the method that eventually got me sound. I installed SL as vanilla as I could on a new drive. The DSDT.aml I originally built was fine, but I had the wrong LegacyHDA in my /E/E. The first step that I did to try to get sound working was what I used to do in Leopard when sound stopped working after a system update: re-apply the Tauruga patch. Not only didn't it work, I think it also borked my vanilla AppleHDA so that every other method in this thread couldn't work either. I spent days building and rebuilding my DSDT.aml (hint: from what I can tell, if your audio hardware is showing up in System Profiler but no input or output devices are showing up in Audio MIDI Setup, your DSDT.aml is fine and it's a kext problem), trying VoodooHDA and all the other legacy kexts in this thread and nothing worked.
I finally thought screw it and completely re-installed SL. The first thing I did was to try another LegacyHDA in my /E/E and it worked right off the bat. So the moral of the story is not to use the Tauruga patch in SL and nuke your install if you still can't solve your problem.