This thread:
http://www.linux-hacker.net/cgi-bin/UltraBoard/UltraBoard.pl?Action=ShowPost&Board=3Com_Audrey&Post=447&Idle=0&Sort=0&Order=Descend&Page=0&Session=
has this link:
ftp://ftp.mindbum.com/audrey/virginaudrey/
to zipped files of all of the Audrey software after getting shell. You should be able to get everything you need there..
Since you seem to have the ability to store files now, you would be able to create your own xxx.shtml files and store them in /data/XML/xxx.shtml.
Read the QNX slinger docs, specifically look at the "exec cmd=" part of the SSI
syntax on this page:
http://qdn.qnx.com/support/docs/neutrino_2.11_en/utilities/s/slinger.html
You don't need shellex or shell.shtml. Write your own exec cmd="chmod +x /blah/blah".
The next snag you will hit is the fact that anything started by the web server runs with 'loser' priority, instead of root priority and you might not have the permission to chmod what you need to.