it's no way with the mid 2012 MBPro 15"
after removing the SUPERDRIVE and putting a Crucial M4 256 SSD inside the optical Bay everything went messy!
;-(
OK i could boot Mac OS Mountain Lion on the SSD and also on the original Apple Hard Disk but when i wanted to run Bootcamp i always had the Boat loader damaged and could only reach windows after having to plug my thumb USB key to restart the Windows 7 Pro Installer and repair disk to be allowed to restore from another USB disk where i previously saved the Windows Bootcamp disk...
I tried more than 10 times but all got was again a black screen with flashing _!
That's why i decided to try another way to climb on the Everest!
;-)
I installed rEFIt that lets you boot from an USB stick and switch easily from an OS to another...
I also installed Paragon NTFS for OS X that lets me format the Apple HD with a single NTFS partition only.
I could then without using Bootcamp reinstall Win 7 from my Saved USB disk and restore it to the former Apple HD.
That was the ONLY WAY that until now lets me switch from one OS to another without being exposed to the damaged MBR boot loader.
It sounds this is a specific issue of the latest mid 2012 MBPro 15", since i didn't have such issues on my former early 2011 MBPRo 15"!
What i read in the How to install Bootcamp is that it's mandatory to have only a single hard disk inside the laptop. I thought this was only mandatory to install Win7 and that i could after plug again the SSD in the optical bay...
But holy Sh... as soon as it was done having again the 2 disks inside the laptop, the mess of damaged MBR boat loader occurs once again...
Congrats APPLE, for this unexpected improvement on the mid 2012 MBPro 15".
Now i have MacOS only on the SSD but also the ability to Run Win7 with VMWare Fusion in a virtual mode, and to get Windows 7 roaring at full throttle i have to reboot from the original Apple Hard disk "only windowsed"
That's all folks
enjoy this hack since it WORKS on the mid 2012 MBPro 15"
I am aware that a lot of people have also been stuck with the same issue after removing the optical bay to have an SSD inside + the original HD.
ANOTHER VERY IMPORTANT THING TO DO:
I also had to improve the shielding of the small SATA lid that connects the optical bay to the motherboard:
Put first one layer of Chatterton isolating tape to protect the naked pins of the connector
then a secund layer of thick US aluminium sheet
a third layer of Chatterton isolation tape
This trick was very useful to have the SSD working at 6 gigabytes allowed by the SATA 3 and avoid the hassle of disk errors or worse the beach balling
