Send and receive PJL commands to USB and parallel printers

We're in need of a well documented example of how to send PJL commands to a printer connected via USB or parallel port to a Windows PC, and receive the response from the printer. The program itself needs to do nothing more than send a simple PJL command such as @PJL INFO PAGECOUNT and receive the response string from the printer. See the attached screen mock up. Keep in mind that this is specifically for USB / parallel and NOT network based printers. The program will need to be able to send and receive information via both USB and parallel ports. Developent should be in VB6, VB.NET or C# and must include detailed comments to enable our programmers to integrate the code into our own projects. The time frame for this project is 10 days from acceptance. Please PM with any questions.