Its pretty easy after you've done some.... I use Tamiya decal scissors (theyre super sharp!) cut them as straight as you can, but if its alittle crooked its not a total loss... I use a penny to put some drops of CA on and use a hobby knife to put glue on one side of the tire to be glued.... make sure you keep the crown of the tire while your gluing, this is the biggest mistake people make, they make the tire flat.
Here's some rear buggy switches made from the center bars of 4w fronts and the two sides of buggy rears.... after you run a pack or two these look factory