Hmm, after looking at iPXE's documentation on this, I think I see what you're trying to do.
First, using an SCCM Operating System Deployment (OSD) works like this: A custom WindowsPE image is created that boots up to an SCCM GUI that lets you select from a number of task sequences, or optionally just start running a specific task sequence.
This PE image can be deployed via PXE, using the SCCM PXE Service Point, A separate WDS server, or probably any decent PXE server(unconfirmed). The PE Image can also be turned into an ISO for burning to a CD/DVD, or converting to a USB.
This PE image can sometimes be rather large, and iPXE makes an interesting (though probably exaggerated) claim that on a gig connection a 200MB iPXE image can download in ~2 seconds. I'm skeptical, but even at 10 times that speed, I think it would blow he standard method (TFTP) out of the water, though it needs to be tested.
Anyway, I said that the image can be deployed from other places besides the SCCM PXE Service point, and that's correct. iPXE wants you to copy a modified version of the PE image to a web server, not necessarily a distribution point. DPs only deploy files to sccm clients, with few exceptions. At this stage in the boot process, however, I don't believe it's possible, although DPs in 2012 do in fact require IIS to be installed.
iPXE provides instructions for the process on their website, the only thing I would do different after giving it a brief overview is use the powershell dism cmdlets to modify the boot image. I see no reason why imageX wouldn't work, it's just a matter of personal preference.
Realize an SCCM DP is not a traditional webserver, and I wouldn't set it up as such. You could keep the files on your DP and configure IIS to serve them up, which may or may not be a risk depending on your environment.