To use the %TEMP% path, you just specify it as a path name. eg:
But to get autorun.inf to do it, well you can't it's not a full scripting file, just the bare minimum to get the program to load and specify an icon to use as the CD.
The neatest way is to create a program that handles all this for you, then as a final instruction, loads Opera from the CD. However, this would need to be created specially, and would cost you.
If anyone else has ideas, feel free to help out.