How do you do mid air refueling in lock on

make your own mission with ie an A-10 refueling on an KC-10. (USA Side)

I found the easiest way to practice to make a (very) long straight flightpath for both player en KC-10.
Set the task of the KC-10 to refuelling. To make a serious connectiontime you should give the players plane about half a load of fuel.
Now fly your way with your A10 to the same alt. the KC-10 has. Default would be 2000. Adapt your speed to the speed of the Kc-10 (default about 500). Get closer very gently, keep your alt. steady just below the KC-10. When you reach within 3 NM the KC-10 will confirm visual contact. Keep on closing in. Don't go in too fast or you have to break away and start over again. Nou open your fueldoor, (default R) and keep the refueling boom of the KC-10 in the middle of your hud. Keep on flying till it locks in. Wait for the message of completion and break away and close your refuel door. That's it! ehh.. well after a lot of practise that is. It's not a simple thing to do and it will give a mighty BOOM if you mess up with the KC-10 loaded with fuel. Be advised that other planes have their fueldoors in differtent places! Best way to discover them if you don't know is to open and close it while you circle around with it in external F2 view and go for the sound ;-). GOod luck.