I've never found difficult since men's and women's jeans often look very similar. As long as it doesn't have any decoration that might be interpreted as too feminine, you're probably OK. I suppose close scrutiny by a clothing expert might suspect something, but I doubt they'd say anything. Women's jeans tend to have a bit more room in the hip and cone in some to the waist. Also, the zippers may be shorter. Still, I've done this for years and nobody seems to take notice.
One of my favs is a Newport News jeans pair with a sewn-in satin pantie that does a pretty good job of tucking things. Another difference, of course, is women's jeans don't have much room in the crotch, but if you position things right I think it can give you more freedom of movement.
