If your Flojet pump is like the one in my Springdale and my Cougar, (pump with the blue locking lever on the input and output connection) you need one of these and a couple feet of clear tubing to attach to the fitting and to put in the antifreeze jug.
http://www.freshwatersystems.com/p-1...FbAWMgodaUsAOw
You should be able to buy just one of these fittings at your local RV parts department, but if not, you can order offline using Google to search for the part number and finding an internet source of your choosing. I didn't buy from this company, I bought mine from Dyers RV.
Just pull the blue lever, remove the input connector and insert your antifreeze adapter, turn on the pump and open faucets until you get pink at all of them.