Path to local pc

I know this is not a vb question, but i am getting desperate. I want to make my own instant chat for my website. I am paying monthly to a vendor now. I want mine to work like theirs.
Their software runs in my system tray and when i get a instant chat a dialog pops up and i instant chat. I have not been able to make this part work.
A button click on my website opens a dialog on my local pc. I have got this to work using a Java applet, but only if i am the one clicking the button. The path to my pc is where the problem lies. The code for the Applet looks like this:
<applet code=MainApplet width=256 height=256 archive="app.jar">
<param name=buttontxt value="Run File">
<param name=path value="c:\test.exe">
</applet>
This path works fine if clicked from my pc, but not from anyone else. I have written a textfile on my website to hold my Ip address and thought i could tie this into the path, but do know how or even if this the way to go. I have posted to a few web sites. Java, vbscript, pythlon etc with no luck. Seems simple enough open a file from local pc from my website. This kinda my last resort before going to a hackers website. Does anyone know how I can set this path ?