How do I tell WebHelp to display a specific topic given a helpkey sent from a program?

We recently incorporated a third-party product into our software. I imported the help topics from the third-party's online help into our company's online help (with the third party's permission). Within the third party software, they have a help button that makes a context-sensitive call to a topic. In order to do this, I enter the URL of my company's online help and then they append a helpkey to it (for example: http://www.mycompany.com/help/WebHelp?helpkey=tabGeneral&language=en-us). The part in italics is the part they append.

I need to know how to set my online Help package (using WebHelp) to open a specific topic based on the helpkey sent via the URL. Given the above example, how do I tell RoboHelp to open a specific topic within the company's online help if the helpkey is "tabGeneral")?

I know all of the helpkeys that can be sent from the third party. I just don't know how to set up RoboHelp to open a specific topic based on the helpkey sent.

Thanks in advance for any help on this.