I realise this is an old thread but I only started aerial refuelling lately, I tried it first with the Tomcat, which I was able to do reasonably well after a bit of practise but the Mirage was something altogether more difficult.
I find the Mirage (when compared to the F14) overly pitch and roll sensitive and with a less sensitive throttle.
After a couple of hours practise and some tweaked settings I was able to refuel it ok. I thought I would share my setting and experience. This is what worked for me.
I'm doing this in VR on Oculus Rift. On my mission, I used a KC-135 MPRS set to fly at 15,000ft and 270 Knots out over the sea on the Caucasus map. For some unknown reason the tanker decided to fly at 217 Knots. Your tanker speed may be different to mine, so you'll have to convert the speeds I mention here.
As I approach the tanker I set the G limit switch to prevent extreme flight modes, and extend the slats, this dulls the performance and help stabilise things.
I practised using x3 empty fuel tanks and x2 Magics.
Trim the aircraft spot on before you start and get the throttle set so that it will gently accelerate by 1 knot every few seconds. I found the throttle was too insensitive, you'd end up giving it a shove to get the aircraft moving and then almost immediately dialling back the power or it would start overspeeding.
I approached the tanker slowly at about 220knots, keeping the horizontal top of my HUD lined up with the centre cross section of the basket (like the HUD top was chopping the basket in two) and trimming the speed with a dab of air brake
I keep my eye on the MPRS fuel pod and try to line it up with the centre of my HUD but fractionally to the right. As I start to get close I dab the air brake to keep the speed at 218 or 219. Don't look at the basket and don't make any sudden pitch or roll movements, above all don't try and chase the basket. If you miss, just engage the brake and drop back slightly.
Connect at 218 knots and immediately let the aircraft run on slightly, so there is slack in the line. From here on it keep watching the speed. If it picked up to 219 or 220 I'd dab the brake and if it got to 216 I'd release it and maybe punt the throttle slightly. After connecting I found it helpful to fix my eyes on the MPRS pod and move the aircraft so it lines up with a fixed point on the HUD, like the compass bearing or something, this would mean raising up slightly behind the tanker but I found it help keep the wandering oscillations to a minimum.
I found it helpful to add some curve into the axis tune in DCS, attached below are screen grabs of what worked for me. Above all smoothness pays dividends. When I started the pilot induced oscillations kept making me think there was something wrong with the tanker or me. It does get smoother, just keep at it.
https://www.dropbox.com/s/g51cz3xs4tk44em/IMG_6803.HEIC?dl=0
https://www.dropbox.com/s/w13worbnhz6jdbk/IMG_6804.HEIC?dl=0
https://www.dropbox.com/s/3k51kcsko4806ft/IMG_6805.HEIC?dl=0