I'm glad to hear you resolved this issue. Can you please reply with the solution so other members of the community can benefit?
It's basically plug and play. We have another (brand new) GC-MSD where an EPC was already installed along with a Deans switch upon delivery. So I just looked inside and found out how everything was installed.
The EPC can only be installed in slots at the back of the GC (you have to remove the cover on top, unscrew a back panel and remove (unscrew) a small metal piece under the top cover. The EPC slides in one of the slots. The cables are already in place and labelled so you just have to plug one in the EPC and remember which number (for the setup stage later). Connect the helium to the EPC, connect a special tubing (part of the installation kit) to the Deans switch inside the GC (there's already a hole on top of the oven, just push the tube through the insulation) and put the panels/covers in place. After that, you have to reconfigure your GC but that is described in the manual.
It's summarized, but if you have any question you can always ask.
Oh, and after everything was installed (and working), we received a message from Agilent asking us when a technician could come to install everything! My boss didn't tell me about that option!!!!