I kept the inside of the Koflach's the same (But am using the snowboard liner) That way i can always go back to how they were. That keeps them sealed as well. The Koflachs had metal rivets already, so I just riveted the snowboard boot uppers and tongue's directly onto the existing boot where the previous rivets were I'll test them out before finishing them up, but I need to find a way to join the boots to keep snow from going between them. Any suggestions on that? I don't think sowing will work because to get the needle through the plastic would require heating which will ultimately weaken the boot.
Also, to keep the rivets from working their way through the soft outer boot, I used some thin metal washers.
Ben, Rockler woodworking has a set of mini wire gauge drill bits and a bit to hold them. I would bond the uppers to the shell with polyurethane adhesive, I prefer sika flex from Home depot-pick the right color, you will get it all over you, and tape up the parts of the boots you are glueing, so they do not get the glue on them, then drill and thread with good nylon thread. Maybe seal over the stitches with some clear silicone.
I would not bother with the stitching the boot together'. I would just get a quality mountaineer gaiter (Black Diamond) or an overboot w/ the rubber rand for leather telemark boots) that would fit over the boot.
_________________ Ride the Pow! ---- Venture Storm R 163 (2010) with Dynafit Bindings, F1 Scarpa Boots, Snowpro Race Plate Bindings * Nitro Retro Swallowtail 171 (DIY Splitboard), Burton Fish 156 * Vans BOA "Klutch" Step-in Snowboard Boot and Switch X Bindings