The only problem is the 68HC58 is EOL. But I bet it is still available somewhere. Its the VPW chip the pcms use, as well as the AVTs. Definitely the best way to do it. But not the only way, and still requires firmware, though a lot of code would be very similar to whats in the pcm. Ive been testing a mega 2560 based circuit with opto-isolators as a front end. Have the VPW triggering interrupts but its not collecting all of them so isnt usable. Still a work in progress.