Below is a link to Grinder's Warehouse, which contains several A-5 sims. The system does yield a small edge even in single-deck.
Its not a bad idea to play a few initial sessions with ace-five, since it requires no real mental effort at all and can be learned in the time it takes to explain it.
Another point: backcounting ace-five on two tables is marginally superior to backcounting hi-lo at one, according to some surprising sims by Alienated at the CCCafe. I once managed to quite easily keep track of five tables with ace-five, in a crowded Scottish casino.