How do I change the default download directory for the R2014a installer by passing a -downloadFolder flag to the install script?

i run out of space in my default download location so i need to change the download directory, but i don´t know how to do this. someone asked already this question but since the answer was, that you should just edit the install script, i wonder how to edit it. and what should it look like? "-downloadFolder E:\downlads"?

i´m starting my installation from an iso file.

thx for any helpful answers