Hello from London and soon Paris, Europe
I just send you a message here to let you know i can do a similar work BUT NOT THE SAME as you described.
And that's possibly why no other developer apply to your job offer.
We way you want it done is a bit unsafe as google may change the way the url is encoded without any notice which would lead your script to fail.
The proper way to do it, and i've done it many times is to get the route from the standard API using a PHP script, and then convert the route into a KML/GPX file which i never did yet.
I can show you a demo on my website by monday 11 is you want me to show my skills