In reply to Fultonius:
If using climbing shoes you may need to stiffen them by adding a bar of some kind.
My first effort was like this using a pair of climbing shoes but i only fitted them with 1 front spike, so not very good if you needed to edge.
I have gone with using a pair of old winter boots now and have removed most of the sole unit, very light but still stiff. Bought a pair of cheap crampons (oxfam) cut the front end off and retro-fitted them on. (had to weld small wings on to fit the T-nuts) have left the heel free.