Triple boot WIndows 7, Windows 8, and Mountain Lion on Macbook Pro

Ok, So I have a bit of a unique situation here I could use some help on.

I've modded my summer 2011 MBPro to have 2 harddrives by replacing the optical drive. OSX Mountain Lion is installed on a single partition of a 120GB SSD. The second drive is 750GB, partitioned as 550GB, 150GB, and ~50GB. I've set the 550GB to act as my OSX homefolder, but I'd like to install windows 7 and Windows 8 on the remaining partitions. It Took a while, but by following this guide, I eventually found a way to install Windows without a CD/DVD drive by following this http://huguesval.com/blog/2012/02/installing-windows-7-on-a-mac-without-superdrive-with-virtualbox/

It worked flawlessly for creating both windows 7 and windows 8 images that I could clone onto FAT32 partitions. However, I have encountered a problem when trying to triple boot. After I put Windows 8 onto the ~50GB partition and tried to boot into windows 7 I get an error that says something like:

error: 0x0000000e The Boot selection failed because the required device is inaccessible.

If I re-clone the windows 7 image onto the drive and select the option to "replace BCD" file for the drive, windows 7 will boot but windows 8 now gives me the same exact error.

I realize this is a pretty extensive setup, but if anyone has some insight I'd love to hear it.

Edit: I've tried installing windows from a USB, but my firmware doesn't let me. I get an error "No boot device detected". I get the same error when trying to use an external CD/DVD drive. As far as I know, only the recent 2012 Retina Macbook Pros and Macbook Airs are able to install windows via USB.

If you have an ISO of Windows 7 and Windows 8, then boot into one of the Windows operating systems and install YUMI – Multiboot USB Creator (Windows). Add both of the Windows ISO installation disks to a USB drive that is big enough (roughtly 4gb should work for both windows discs).

Next, install Windows 7 and Windows 8 as you normally would booting from the USB drive. Also I would like to make a note here... if you go into the "advanced" drive configuration and format/pick the drive that you want to install Win 7/8 to then it will not attempt to "make two separate partitions". I never let the windows installation automattically configure the hard drive. I've not ever had the windows installation create magical secondary partitions as is stated in the tutorial that was listed.

Also, you can slipsteam the drivers and most up to date service pack for windows following this tutorial to make the installation for windows smoother, especially since the drivers for your mac will then be "built" into the install disc.

Good luck =D