I used this strategy for UMVC3 and MVCI with my jpac (same manufacturer as ipac) interface. It's kind of tricky but works well.
This has been my go-to for recent Steam games that either only do xinput for two player, or have terrible keyboard layout (needing space, enter, backspace and esc to navigate through the menu...but when using 360 pads it's accomplished with just the A and B buttons...that's frustrating on a cab with only so many buttons.)
I apologize for any word vomit, I can clarify or answer questions you might have about this approach.
It goes like this:
interface (keyboard keys) -> vJoy virtual direct input pad -> x360 virtual xinput pad.
First you want to emulate a directinput pad with keyboard keys using vJoy:
http://www.headsoft.com.au/index.php?category=vjoyMake a profile with that and ensure that all of your buttons show up fine for both players in the Windows 'Set Up USB Game Controllers' control panel. You may have to set up/down/left/right as an analog joystick, not a POV Hat - I think diagonals didn't work for me if I did it as POV. For vJoy to work you need to have it running in the tray, I recommend saving your profile and loading vjoy with the -file command pointing to the .ini you created.
Now copy x360ce into your game folder (64bit for MVCI, forget which one for UMVC3):
https://github.com/x360ce/x360ceRun it, it will ask to drop the xinput dll it needs in the game folder.
Let it download the recommended settings for each vjoy gamepad, just click ok.
At this point, launch x360ce from inside your game folder and map each vJoy gamepad into 360 buttons as you would like (whatever makes sense for the game). Once more make sure all buttons work and light up the xbox buttons in x360ce. You only have to map the buttons you need (I had no use for the guide button, right joystick etc)
Please ensure that 'Block Keys' is enabled in vJoy - this will prevent your usual keyboard keys from going through from your encoder while vJoy is running. This is necessary because otherwise the game may react to keyboard keys first and ignore your joystick. Be sure to click 'OK' in vjoy after you do this and not 'Close'.
So doing this UMVC3 will work.
MVCI actually needs one more step to this process - if you launch through steam you need to tick the 'disable DirectInput' option.
Or a better alternative, your shortcut to the game's exe (located for me in C:\Program Files (x86)\Steam\steamapps\common\MARVEL VS. CAPCOM INFINITE\MVCI\Binaries\Win64 ) needs to have -NoDInput as an argument. (I had to process snoop to figure that out.)
Without somehow disabling directinput, MVCI will see both your vJoy directinput pads (which don't seem to work all that correctly as is) and your x360ce xinput pads at the same time leading to some wonkiness. This (along with key blocking in vJoy) ensures that the only thing MVCI sees is your emulated 360 pads.
Ok so the games should work and recognize your pads, outside of your frontend. If they don't, go through each step and check that you're seeing button inputs where you expect (USB Game Controllers in windows to check your vJoy directinput pads, and then x360ce inside your game folder to check your x360ce xinput pads.) If you're having any issues let me know. The only problem with this approach is - what about games that don't need these emulated pads or emulators that I've set up for keyboard inputs? How do I set them back?
Well, there's some things we have to account for. x360ce emulation ends as soon as the game exits, so that gets rid of your emulated 360 pads when the game ends. Great.
What we still need to do is disable vJoy and the emulated pads when we're done.
Running a vJoy command line with -exit will exit the program, but the emulated pads still exist. You need to disable the vJoy driver itself using a microsoft exe called devcon:
https://quirkyvirtualization.net/2017/09/16/download-devcon/So procure the version of devcon you need for your os.
And run from command line:
C:\Program Files (x86)\VJoy\VJoy.exe -exit
devcon.exe disable "HID\VJoy&Col01" "HID\VJoy&Col02"
Likewise when you start a new game you can run
C:\Program Files (x86)\VJoy\VJoy.exe -file "my vjoy setup.ini"
devcon.exe enable "HID\VJoy&Col01" "HID\VJoy&Col02"
You can add these to a batchfile or autohotkey if you're familiar with that, or to your frontend if it supports arguments before/after launching games.
Thanks to TheManuel from his Mortal Kombat X thread for the idea! He has an autohotkey/rocketlauncher version of those batches here.
http://forum.arcadecontrols.com/index.php?topic=144993.80