Well of course they're not 100%, but I think they'd certainly work How will you attach them? From the inside or just attach them to the outside? If you could work the angle from the inside I think they'd do just fine
I used nylon bolts for mine. There in the drawers at Home DePot in the bolts/nails aisle. Use a good hand held pencil sharpener to add the point. I just drilled holes in my boots and epoxied them in.
I'm using pen tips on my scratchbuilt boots, too. the pegs, above, aren't 100% accurate, but do look pretty cool.
Quite long though, careful you don't trip up on them, or gouge your/someone else's leg!
Depending on what your soles are made of, you could drill into them to sink them back a bit, then epoxy them in. They'd then be pretty firm, and not stick out too far.