This stuff is meant for patching concrete and making mortar beds. It lacks a coarse aggregate component so it really needs to be supported by something solid underneath AND on the sides after it cures. My guess is the edges would crumble under punishment if you don't support them with forms (and leave them in).
Most people use concrete mix for pavers. Concrete is meant for 2" or thicker applications, but I'm guessing that using forms to pour the concrete directly onto the slab (i.e. you're not molding pavers then just setting them down) would make them "one" with the slab and will not crack unless the slab under it cracks. Contact Sakrete to ask which of their products works best (they are very good about answering questions quickly).
If it were me I would mix 2 parts unmodified thinset to 1 part pea gravel. This mix is much stronger than concrete and thinset is formulated for thinner applications. You still need to pour into forms onto the slab. If you don't want to see the pea gravel, mix a small batch of just thinset separate of the thinset/gravel mix. Fill the form most of the way with the thinset/gravel mix, then skim the top with just thinset. Honestly, your pavers are so thin you may not need the gravel at all. Pour 1/2" of just thinset into a ziploc lunch container and see if that's strong enough for you. Keep in mind that thinset is very sticky so put a layer of Vaseline on your forms so you can get them off. You won't need the full 72 hours for the thinset to cure. That cure time assumes it is buried under tile. You should be able to remove the forms in less than 24 hours.
If you go the thinset route you may be tempted to buy modified (fortified) thinset (more expensive means better right?). Modified thinset is just able to cure without breathing...you don't have that issue and will gain nothing from the extra expense.
This thinset comes in white or gray and can be colored using cement dye...or possibly grout dye.