I know my DH often thinks of babywearing as a "woman thing"; perhaps marketing a model designed *specifically* for men would help vs one that can just be "worn by men, too".
Lots of men in the marketing materials in a variety of activities, not just the typical street scenes, perhaps an adjusted design to accommodate wide shoulders and larger statures (maybe even a "beefier" design with wider straps to look more manly lol), plain colors, not just "manly" patterns (think gradients of grey, tan, green, dark blue - my dh is not a pattern fan and once he finds a color he likes, he sticks with it on everything), and some additional technical features like pockets, clips, etc.
Contests are fun too - maybe design one around the male population - picture contest, new design feature contest, most unique use? etc. Freebies with purchase that are techy in nature, related apps?
eta: oooh just thought of another idea: get them out to stores/sites that appeal to guys - I'm thinking something like Think Geek if you can put a fun spin on it. :)