PREPARING THE SHOE:
Your shoes must be new, or, clean and dry . The spot where you will place the Velcro must be smooth.
Cut off about an inch and a half of the self-adhesive Velcro strip for each shoe.
Attach it to the back heel of the shoe. Allow 12 to 24 hours for the strip to reach maximum adhesiveness.
If your shoes are dirty, or have a groove in the heel, the strip may not adhere securely. Epoxy-based glues, Shoe Goo, Gorilla Glue, Velcro Glue, Seam grip, and hot glue can be used.
(Please read below, from Michael Cartwright's NW Ultras Blog, for suggested solutions.)
I discovered the outdoor person's version of duct tape years ago: when on expeditions I usually carry at least one tube of SeamGrip: besides its obvious function of sealing tent seams, I've used it over the years to deal with crampon holes in snow gaiters, tears in Goretex jackets and even emergency ripped tent repair. It needs to dry overnight but after that, it bonds exceptionally well even on dirty surfaces and does not become brittle over time, even if exposed to plenty of UV.
What follows is my method of using SeamGrip to do a clean job of mod-ing your shoes for a permanent Dirty Girl Solution.
The tools required are some form of sharp crafts knife to cut the Velcro and a tube of SeamGrip (which you can get at REI).
Obviously you can cut simple square chunks and slop them on with great gobs of glue. this works if the shoe has a smooth surface on the back of the heel and looks great on black.
More complex surfaces and lighter colors require a bit more finesse.
Sculpt your Velcro while still on the backing taking care to keep your fingers away from the business end of the knife.
Try it for size and keep sculpting till it fits in the right spot on the back of the shoe. I try to keep them as low as possible to get more use out of the gaiters.
Make a glob of SeamGrip on a piece of paper. Remove the backing from the Velcro and use it to scoop up some SeamGrip. I find this cleaner than trying to apply the glue to the shoe or to the Velcro directly. Wet your fingers before working with SeamGrip if you don't want the stuff all over your hands.
Place the Velcro and use a piece of paper towel to dab it into place and wipe off any excess glue. Because of the curved surface, the edges will curl up. Let them. Leave for 2-3 hours and then returns and dab again. This time apply plenty of pressure for the final stick.
Leave to dry overnight. Perfect.
WEARING THE GAITER:
Gently splay OPEN the hook with a flat edged blunt blade or flathead screwdriver.
This will make it easier to hook the gaiter under the shoelace.
Put on your socks as usual.
Pull the gaiter on over the socks.
Put on your shoes and tie as usual.
Pull the gaiter over the shoe.
Hook the front hook under the shoe lace on the front of the shoe.
Attach the rear Velcro on the gaiter to the strip on the back of the shoe.
Adjust the gaiter over the top of the shoe.
GO OUTSIDE AND GET DIRTY!