I'd say, put it somewhere else. Unless you wear your pants fairly baggy, it may be hard to hike up your pant leg enough to draw the knife, especially with stiffer denim.
My Carcajou's blade is about 3 in, and with the sheath, it makes drawing from the leg impossible. Also don't get a fitted sheath (kydex, but mainly the poly-stuff) , beause it must be strapped to your leg very securly in both directions. Plastic sheaths are also stiff and will, be uncomfortable, especially with the bands/straps on you leg being all tight. Also keep in mind that a strap will probably have to be above and below the buldgy part of the calf.
TOO MUCH STUFF TO THINK ABOUT. So go look for some other options, I'm also looking for another out of the way place to put my fixed.
Please post any other carry options for a fixed blade.