How can I boot my MacBook Pro from a DVD to update my SSD firmware
You should know there is no such this as "BIOS" on a Mac (the equivalent system is called EFI, but you don't boot into it to change settings). To boot from a DVD or any other external medium, you'll have to hold down the Option ⌥ key while booting.
Then you'll get a list with all the bootable devices and there you can select the device you want to boot from. 

Or you can go to System Preferences > Startup Disk to select your disk and then reboot. Then you'll also boot from the disk.