Here is an interesting thread on the same thing (female bikers and runners) that I found last week:
http://forums.teamestrogen.com/showthread.php?t=34260
On page three one person lists some corrections (not accomodations-like insoles) that you can do:
"Dropped Met Head Program
To be done over the course of 6 weeks, and maintained there-after.
Consists of two parts: first stretching, then strengthening. Done in that order for every session.
Stretch by folding your foot like a taco shell. Hold your bare foot in both hands. One hand on the left, one hand on the right. Thumbs parallel on top. Line up your fingertips between the 1st and 2nd met heads or on the 2nd met head, whichever feels better. Press down with the heels of your thumbs while you press up with your fingertips. You are essentially folding your foot in half lengthwise. (restoring your metatarsal arch and then some) Hold for 5 seconds. Do 10 times in a row.
Strengthen by working the muscles of the forefoot that support your metatarsal arch. Make a fist with your toes as tight as you can. Hold it for 5 seconds. Splay your toes out as wide as you can. Hold it for 5 seconds. Do 10 times in a row.
Week 1: do the session 3 times a day, spread through-out the day. (morning, noon, and evening for example)
Weeks 2-6: do the session 6 times a day, spread throughout the day. (every 2 or 3 hours, for example)
Maintain by doing however many sessions you feel you need to keep your met arch lively."