GTA IV with (old) Xbox Controller - Triggers won't work right.

Hello.

I have trigger issue and I hope someone here can help me out.
I'm using old Xbox controller (that BIG one) customized with USB connector and XBCD in Vista.
Button mapping is now like this:


I mapped triggers as buttons 11 and 12. 'cos I didn't get anything else work, but buttons.
Otherwise controller works right, but triggers are digital (Full ON/OFF)
in other words - No Free Aim and full throttle or none...
With XBCD I can map triggers to slider or Z-axis, which makes triggers analog but I dont know what I should edit (number code) in xbox360cemu.ini file to make GTA IV recognize triggers.

So, what should I do to make triggers work properly?

Sorry my confusing english.
Hope you understand.

ps. I've posted this also to GTAForums if some here or there have solution to this problem.