be careful. That optical drive is ATAPI. not SATA, which the MacBook Pros run SATA Drives. If you can somehow shoe-horn the SATA drive into the optical bay, and assuming they exist, you would have to find a way to interface with the Intel AHCI SATA ports, which you can't just parallel off another. There might be a way considering the chipset in them supports at minimum 4 SATA devices, but you will need to find pads to do it.

That MBP also only has SATA 1.5Gbit/s so a SATA-II SSD, while may be fast will still max out at about 130MB/s realistically (like the 2007 iMac C2D 2.0Ghz white with an OCZ Vertex-II which is a SATA-II SSD on a SATA-I controller)

I think you would be better putting windows 7 and 10.6 on it. Otherwise, use the ExpressCard slot to put an eSATA port on it. With a Syba eSATA/USB II 3-port ExpressCard adapter for my 2008 MBB (nVidia GeForce 8600M GT) it will boot off the eSATA with the ExpressCard (Return of bootable expansion bays!!!) assuming you have an expresscard. I can't remember if that gen of 15" did have it. I think they ommited FW800 for some reason)

Your alternate would be to carry a 2.5" usb 2.0 portable case with the drive in it for data you need access to.

Of course in the USA, SSDs are down to less than $1USD/gig. and getting cheaper!