screw: https://www.mcmaster.com/mv1489684848/#91099a220/=16sjhzs
t-nut: https://www.mcmaster.com/mv1489684848/#90973a400/=16sjhyt
Then add line 24 snaps. You will not need the snap studs (the part that secures the socket), as this is replaced by the t-nut and screw.
Many folks prefer pull the dot snaps, from dotfasteners.com found here: http://www.dotfasteners.com/products/?wfc_applications=687&wfc_product_brand=897
Again, with dot fasteners, you will not need the post/eyelets. You only need studs, sockets and and caps. If you are buying plain line 24 snaps from somewhere, they typically come with all the parts together.
Don't forget the proper tools to seat your snaps!!
I just made this one just a couple days ago, it was my first IWB holster: