I only got a OTG Host cable about 2 months ago, and only just got it working.
You will need the following:
USB OTG Host cable
USB Y cable (or whatever it's called - at least that's what I used)
A rooted phone (I am using the GSM Razr Maxx XT910 on CM11-nightly)
USB OTG Helper (Play store)
USB Host Controller (Play store)
Script Manager - Smanager (Play store)
Install all apps and extract attached script and copy the file (ThumbDrive.PreMount) onto your phone/sd-card memory.
(Note apps must be granted superuser permissions)
1. Connect your charger to power and connect your phone.
(Before we can begin, we must first find where the drive is. Open USB Host Controller, and under settings make "Dmesg display mode" continuous". Under the USB tab, look at the log at the bottom and you should see something about the device being rejected due to insufficient power or something like that. Mine is 3-1, your's will probably also be, but if it's not 3-1, you will need to change the script accordingly with a text editor.)
2. USB OTG Helper may give you a popup, just click cancel.
3. Now in Smanager, run the script you copied onto your phone. You must run it as a script, and give it SU permission. Just click the home key after you've run the script.
4.1 Now open USB OTG Helper and click mount.
4.2 You'll probably get an error, but you can ignore this.
5. Your drive should be mounted. Look for it under /storage/UsbOtgDrives/drive_1 (I use Solid Explorer as my file manager and it even added some shortcuts on the left - but not initially though).
You will have to do this everytime you plug a device in, but it's very quick once you know what to do.
I'm just putting this out there because I know it's a function many have not got working. I know there's already a lot of resources on this topic, but frankly they never really helped me. This thread guided me in the right direction though: http://forum.xda-developers.com/show....php?t=2050925