Kevin hope this helps some.
I believe you want it with the 3 position flap switch....secon from the left next to the aux 5 dial.
If so and you don't use the slider....

First deactivate the slider by going to code 17 and scroll down one to FLAP and set it to INH ( you may need to readjust your flap linkage if you had not already done that. You will also need to go to AUX 2 and also set it to INH so you don't accidentally hit the aux 2 switch deploying only one flap.

Next go into any open mix and
Assign the mix as FLAP->AUX2
then set the OFFSET to -100% on the top number
(If the servo still works backward you can make it a +100% by pressing TURN) test it first on the servo monitor page (code 75) so you don't force a flap the wrong way. They should show movement in opposite directions....1 up ...1 down.

Skip the switch position select page
I think you can leave it in the NORM type of mix under MASTER ...its been awhile, I am not sure.
Then exit out of the program mix

Now enter code 66 for flaps
Disregard the ELEV Mid and ELEV LAND portion for now...that is for adding up or down elevator trim adjustments as you deploy flaps.

On the right side of the screen you will see FLAP with MID and LAND settings.
set the physical flap switch to the mid position and increase the numbers say to something like 60 for MID Note you can select U or D meaning up or down ....you may need to select U just depending on servo reverse or your unique installation. I always seem to end up using U. You will see the flaps start to move. Keep increasing the number until you get them to the takeoff flap position you want.
Next do the same for the landing position after you move the FLAP switch to the land position. At first the flaps will go back up until you have increased the number under the LAND position.

Later you can add in any elevator trim adjustments by going back into code 66 if needed.

If you use servo slow function I believe you will need to slow both of the channels or the one on flap will move slow and the one on aux 2 will be instant.

This should get you to what you want or at least closer.
BC