First off I should say I own 3 X10 Mini Pros with nAa's MiniCM7 2.2.0 with his kernel and that's what this guide is for. I have not tested this on any other device!
Auto brightness & keyboard lights work fine without any third party solution. The only problem I have (which happens rarely), is that the kb light doesn't come up after unlocking the phone and locking it right after then unlocking it again using the keyboard. And to fix that, just get the phone in some light to reset the sensor and bam it's working again, so that's no biggie. I think that's just a bug from the ROM itself since it happens on all 3 devices.
To get Auto Brightness working:
1. Goto Settings > Display > Brightness > Enable Automatic Brightness
2. Goto Settings > CyanogenMod Setting > Display > (I have ultra brightness disabled) > Automatic backlight >
Light sensor filter > Disabled
(Important ) Use Custom > Enabled
Edit Other levels:
Lower Upper Screen Buttons Keyboard 0 3 41 255 255 4 15 81 255 255 16 63 143 255 255 64 249 186 255 255 250 infinity 255 0 0
Allow light decrease > Disabled
An alternative to for fixing the keyboard lights (Just the Kb lights only, not auto brightness) is using D4rKn3sSyS' Kfix 2.3.
Just install that, turn the light levels all the way up and bring the light sensitivity all the way down (to the left), then adjust to your liking.
I don't use D4's Kfix since I have everything working fine without it. This is just for others who want to try fixing with a 3rd party solution.
Hit "Thanks" if I helped.