Right. So I've been looking at VBS Scripts and batch files recently and autorun.inf would really be the cherry on the cake (don't worry I don't plan on using it as a tool for evil). I know that it has been turned off by default on Windows 7 onward but I read somewhere that it is still on for CDs. So naturally, I wonder - Is it possible to make the USB drive look as if it were a CD to make autorun work?
a USB pen drive and a USB CD tray have the same device class (USB mass storage device class). the problem is that despite the same device class there are other parts in USB protocol that differ (interface descriptors, configuration descriptors, endpoint descriptors,...) These usb descriptors that are also responsible for what driver / kernel module is loaded by the os, are hardcoded in the firmware of the device. your only chance to make a pen drive appear as a CD is to change these hardcoded descriptors or what is easier, to build your own device using a microcontroller with USB functionality in that you program your custom descriptors. Note that kernel modules and drivers are based on standardized protocol so your descriptors have fit these standards for the device to work.
In http://www.beyondlogic.org/usbnutshell/usb1.shtml is more information about USB protocol and the descriptors...