I would advise strongly against using paracord for this application. There are a lot of factors not being taken into consideration.
My first piece of advice would be to hop over to saddlehunter.com and check out the climbing methods forum there. You can search and find endless information on aiders, and other climbing methods.
A lot of it depends on how many step aiders you're looking to build. I think anything beyond a single step aider is asking for trouble for an inexperienced climber. I personally use a climbing sling girth hitched around the stick post, and laid over the bottom step. You can buy them in various lengths, they are sewn by a certified facility and rated for climbing use, they're cheap, they're light, and it takes the fiddle factor out. I personally use a 60cm 16mm climbing sling. You can use any number of things (hose, a piece of rope, a piece of webbing, etc) about 6" long and tape it to the sling where your foot goes. This will assist in keeping the loop open.
Be careful, lot's of folks are trying to go down this road, and they are not equipped mentally or physically for the increase difficulty in climbing.