When I have made these, the spiral has been easy to thread out. One end was flexible enough to slightly bend to allow me to twist it out. THen I was able to use the original cover as a guide to punch the holes in my cardstock, then thread the spiral back on.
I have also tried cutting a straight slit from the hole to the edge of the cardstock, then slipping it onto the spiral, and adhering it really well so that the slits barely show. Up close you can tell the paper was cut, but not from a normal distance.
Hope this helps!
I will try to link to mine...The carstock itself (the blue) is punched only and threaded on the spiral, the polka dot paper is cut with straight slits and slid into the spiral.
Gallery at Splitcoaststampers