This is how i would do it, although I'm not sure of the exact ratio of ingredients. i would experiment to figure out exactly how you like to do it best.
Grind up some leaves, (i would use something like a grinding stone and a blunt object. you could go out and buy a mortar and pestle, but I'm cheap. I'd probably get a bowl and a spoon).
add water and a grain alcohol (like everclear or vodka). depending on the amount of water/alcohol you add will vary the strength of your cologne/perfume.
after you mix all the ingredients, run them through a strainer (like a coffee filter) to get rid of all the leave bits and then you can bottle it as you please.
For a lot of additional information on the subject, check out this website. they have tables with how many parts of each you want to add. (think of your leaves as oil. when you grind it up, the moisture you obtain will be the oil/fragrance part of the ingredients)
Also, if you have a lot of extra mint leaves, i personally love to put it in my tea, or cocoa. it adds a nice little kick of flavor.