Ron Brunckhorst's Alpine Rock and Ice Guide to Montana is the best (and only) reference for those planning to climb one of the numerous rock climbing routes in the Cowen Cirque. Tom Turiano has a great section on the peak in Select Peaks of the Greater Yellowstone.
There is a sign at the junction for the East Fork of Mill Creek, just after you cross the bridge over that fork.
A trip report for Mount Cowen in January of 06 is on my web site at...
The coordinates currently place the peak in Mongolia. There are a few other peaks incorrectly hanging out there too...
Should be fixed now! Thanks!