Simple spandex boot cover tutorial:
Get yourself a pair of cheap flats, cheaper the better.
Sew yourself a sock out of your spandex material, but leave the bottom open. Pry the sole off the shoe (this is why cheaper is better, usually the construction is a bit lower and it'll be easier to remove the sole). You don't need to completely remove the sole, just pull the edge up enough to tuck the edge of the fabric sock inside. Then glue or sew the sole back on securely The top of your flat should be inside the sock now, giving you spandex boot with an actual shoe sole on the outside.