Maybe, I don't know. I'm very close to doing the one leg forward, one leg back splits (both ways) and never had all that much training or routine stretching. I have had a pretty good natural flexibility though so that certainly helps. You can of course just try to do the split. By attempting it regularly, you should eventually be able to increase your flexibility and get lower down into the split. Stick with it long enough and hopefully you'll get all the way down into it. If you've got decent flexibility to start with this might be the simplest way to go. And it's probably the most straightforward answer, too -- want to do a split? Just keep trying to do one, you'll get it eventually.

As for other stretches that might help, I'm not sure. I guess you'd want to do things that do some work on the hips and upper legs, more on the inside/groin region than the outside, I'd think. I think those are the primary areas that would possibly restrict your ability to do a split. But there must be others who know more about this than I do. Maybe they can give you some more suggestions. I hope this is of some help though.
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James Marshall
marshall@astro.umd.edu http://www.astro.umd.edu/~marshall