Wow, you can find Roger Rabbit-related stuff in the strangest of places. Your old pal Al happens to be a big fan of Duke Nukem and while watching a interview with his voiceactor; Jon St. John I was quite surprised when he did a Roger Rabbit impression. And a darn good one to. He goes on to say the reason for doing this was because he used to stand in for Charles Fleischer. Quite an interesting bit of trivia there.
Skip to 17:20 to hear his Roger voice and again to 33:05.
Hail to the king baby!