Simple perl script + generic html code to write a log file safely & cross-domain

Scenario: * I'm in one room with an excel test logging Excel workbook. * My usability test participant is in another room behind a one-way mirror clicking on an HTML prototype served on some random domain xyz.com. * Whenever my participant navigates to a new page, the prototype will fire off some GET/POST to a script on my personal domain with information about the page and timestamp. * When I enter a log note on my logger Excel workbook, my macros will fetch a text log file from my personal domain and populate the "page viewed" column in my spreadsheet with the filename my participant loaded as I type my notes. I have already written the Excel VBA code for this (and have a good idea what should be in the JS code). What I need is a Perl script to do the logging and some JS code I can tack on to any prototype to do the POST/GET'ing. What I need: 1. Simple plain HTML/JS to asynchronously fire off (and forget) an XMLHttpRequest POST (or Get) from arbitrary domain [login to view URL] to my ([login to view URL]) domain with a timestamp, the http file name, and possibly another variable or two. (No dire need to get anything BACK from the server script except for debugging.) 2. A perl script that will run on my CPANEL hosted ([login to view URL]) [login to view URL] domain to receive the variables and write them into a short, web-accessible text file (on my [login to view URL] domain) in some format, easily parseable in VBA using Split(), etc. (So my excel macro can fetch the log text file and see information about what file is currently being viewed by my usability test participants in the next room.) 3. The perl script should be safe with simple controls on who can easily use it. Perhaps a keyword among the data sent with the POST/GET that can be hashed and compared by the perl script? (I can always update the keyword on the JS and the hashcode on the Perl script from time to time - if the perl script returns anything on error or success, it should probably be the result of hashing the keyword that was sent in the POST/GET.) Also, perhaps some RegExp translations or other checks to prevent bad actors who guess the keyword from doing "buffer overflow" or whatever it is that hackers so to corrupt my server? 4. It should all be well-commented code so I can make updates. 5. You must agree that your work product is original code, i.e., not contain any copied JS or Perl code that is proprietary or covered by any license, and that it is copyright-free, and that I have the total ability to use, copy, modify, distribute this code without any restrictions whatsoever. (This is required by the companies I work for.) By hiring you to write this code, I own it and can release it into the wild without restrictions.