If you are indeed trying to install WHS 2011 here's the easiest way. Install WHS 2011 - all the way - on another computer that has a monitor
When you are done, just move it to your HP box and you should be good to go.
I screwed around with USB, Config.ini, keyboards, pressing keys certain number of times to supposedly get it to boot off the USB, past the dialogs, etc. - turned out to be irrelevant. I got the idea from another thread here on the forums.
And to show you how well it can work, I installed WHS 2011 on my new system drive on my Mac Pro
I pulled all the drives in my Mac Pro (safety first!), put the new WHS system drive in, booted off the DVD and installed WHS 2011. I just had to be there for each reboot to hold down the option key and pick the WHS hard drive to boot off of. The only thing I didn't do during the install was activate it. I also didn't install updates on the initial install (declined them). Once I got the install to the point it would boot, I shut it down, moved the system drive to my EX490 and lo and behold, it came right up! I RDPd into it, ran all the Windows updates, added the Silicon Image eSATA driver and then I went ahead and activated it. Has been running for a little over a week now with no problems.
So you can mess with the USB key if you want - but it's not strictly necessary