It's possible to install Snow Leopard on the MBP, but the process to do so is a bit complicated. You will need access to a Mac that does run Snow Leopard.
The simplest solution is to clone a Snow Leopard 10.6.8 system to your MBP. First, add a new partition to your MBP:
Step One: Put the MBP into Target Disk Mode:
You need a Firewire cable to connect the two computers. Then follow these instructions: Transferring files between two computers using FireWire. You will boot the MBP into Target Disk Mode and boot the other computer normally.
Step Two: To resize the drive do the following:
1. Restart the MBP and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
After the main menu appears select Disk Utility and click on the Continue button. Select the hard drive's main entry then click on the Partition tab in the DU main window.
2. You should see the graphical sizing window showing the existing partitions. A portion may appear as a blue rectangle representing the used space on a partition.
3. In the lower right corner of the sizing rectangle for each partition is a resizing gadget. Select it with the mouse and move the bottom of the rectangle upwards until you have reduced the existing partition enough to create the desired new volume's size. The space below the resized partition will appear gray. Click on the Apply button and wait until the process has completed. (Note: You can only make a partition smaller in order to create new free space.)
4. Click on the [+] button below the sizing window to add a new partition in the gray space you freed up. Give the new volume a name, if you wish, then click on the Apply button. Wait until the process has completed.
You should now have a new volume on the drive.
It would be wise to have a backup of your current system as resizing is not necessarily free of risk for data loss. Your drive must have sufficient contiguous free space for this process to work.
Step Three: Clone using Restore Option of Disk Utility
- Boot the MBP into Target Disk Mode.
- Open Disk Utility from the Utilities folder.
- Select the destination volume from the left side list.
- Click on the Restore tab in the DU main window.
- Check the box labeled Erase destination.
- Select the destination volume from the left side list and drag it to the Destination entry field.
- Select the source volume from the left side list and drag it to the Source entry field.
- Double-check you got it right, then click on the Restore button.
Destination means the new partition on the MBP's drive. Source means the Snow Leopard computer's drive.
Alternatively, you can clone the Snow Leopard system to an external drive, then restore the clone after connecting the external drive to the MBP.
A more complicated process involves using a 16 GB USB flash drive to which you would install Snow Leopard using the Mac that runs Snow Leopard. The Snow Leopard DVD installs 10.6.3, so after installing Snow Leopard onto the USB flash drive you need to update the system to 10.6.8 using the Mac OS X 10.6.8 Update Combo v1.1. Now, boot your MBP from the USB flash drive and clone the Snow Leopard system to the new partition on your MBP's hard drive.