I was recently in your same situation, was putting together my cabinet and began working on the software, I could live with the "left right" issue, but really wanted to have high scores. I checked out the thread and followed the directions as listed and it was a very easy process. Using the Mame Compiler 64 was very easy. It spells out everything you need and where to get it and the steps to take to compile.
Now when I launch games from MALA I get a blank screen briefly and then the game comes up. No warnings, no left right, no loading artwork, etc. That is great, but the best part is being able to show off your high scores when they come up. It's all about being number one on the list.