It looks like most people use glass sleeves instead of small scrap pieces. It seem like the sleeve has to go through the deck and not just stop at the inner surface.

I only used Maroske fittings on one boat, but that's what I did - pulled the glass sleeve right through the deck. The epoxy was 'pulled along' the sleeve and seemed to saturate everything well. (Gravity helped, as the deck was upside-down at that point.)
I used a countersink on the holes in the deck before I put in the sleeves, to make sure that there was plenty of epoxy on the top surface -you'll want to countersink or 'break the corners' on the holes at the end to prevent excess wear on the shock cord and lines.

BTW, I mail-ordered the fiberglass sleeve material from Soller Composites, and they shipped to Canada with no problem (and no outrageous shipping fees). They say they ship world-wide.