To Change the cartridge on an Eclipse KPS3029 faucet you need to pry off the button that covers the set screw.
Undo the set screw with the Allen wrench that comes with the repair kit.
This is inside view of the handle and set screw.
Remove retainer with reverse socket provided. Requires an adjustable wrench not provided.
Use adjustable wrench to remove cartridge holder.
Remove Cartridge. To reassemble reverse steps. Make sure the two small knobs align with matching sockets in body of faucet. Make sure you have right cartridge. See article on cartridges here.