Honestly, I have never heard of any exercise routine for stretching the feet beyond the standard "flex-and-stretch" of the foot. I myself do these while watching TV, but I also do rolling of the toes and circles of the feet (more for the ankle).
There are rolling bars that used to be popular for working the feet.
I've seen some "torture devices" for stretching the feet. Log onto www.ebay.com and seacrh for "male ballet" and be sure to check off the box that says "in titles and descriptions." Currently on the second page there is an item with "ballet boots" in the title. This looks like a device that straps to the lower leg in which the foot is strapped down in an extension position. I don't know if it works, and it reminds one of the "split maker." The split maker was a device that held the legs out like a split, and it had this crank mechanism the would pull the legs farther apart as you sat with the legs pointing out in opposite directions as far as you could go. With the legs strapped in, the goal of the crank mechanism was to force the legs towards the 180 degree position. Go figure! I wonder how much the force could be on these devices...enough to rupture your muscles and cause scar tissue that would further limit your abilities? I think so!
I would not recommend forcing any muscle group. There are many body builders that stress their muscles to extreme with weight. The muscle tissue tears and scars, and that makes the muscle look bulky. But just ask an old body builder who's torn muscles to flex and bend.
Never do extremes. Protect your muscles. Stretch slowly and surely, and never force any stretch to painful extremes. "No pain no gain" does not apply in dance...the body gives pain to limit extremes that may injure it. Tear the muscles and get scar tissue and you'll be side-lined.
balletboy[/i]