AutoIT Implementation Guide For RunOnceEx?

I have searched through hundreds of scripts and posts and I am struggling with AutoIT. Can someone please help me with the last few pieces with regards to "running" the scripts during UA install using RunOnceEx method. Or point me to a post as I cannot find one at all that covers this topic, sorry. Also the help files within AutoIT don't cover running scripts from U/A CD's.

I can write a crude working script through reading these help files, and I can compile this script into an .exe but what I want to know is:

1]Where does the compiled .exe go? In the $OEM$\$1\Install\Apps\ProgName folder?

2]Are any switches necessary?

3]Does the <progname>setup.exe or .msi that you are calling go in same folder too?

4]Does the path at start of your script have to relate to where the setup.exe is during install stage? i.e. on the harddrive?

I can successfully launch an AutoIT .exe from within Windows and install a test app, but as soon as I try anything with RunOnceEx it goes pearshaped. It normally says "error in line <whatever>".