How can I boot my MacBook Pro from a DVD to update my SSD firmware

I have a MacBook Pro 2.3 GHz Intel Core i7 (mid-2011 model) running OS X 10.8.2. I upgraded to an SSD which I bought from Crucial and works just great. Crucial sent an email recommending I upgrade my firmware to get even better performance from my SSD.

I downloaded the firmware to my desktop in the form of an ISO file from the Crucial website, and the instructions told me to burn this to a disk and change my boot order in order to boot from this disk. I burned the disk but subsequently have not been able to get a bios screen or to be able to boot from the DVD I created. I have tried holding down the C key but nothing seems to happen.

What do I need to do to complete the installation of the firmware?

The guide provided by Crucial here is quite PC-hardware centric, that's why they talk about BIOS, I guess. Forget BIOS in a Mac context.

You say you burned a DVD. I've downloaded the ISO file from the update page, burned a CD and I couldn't boot from it either when pressing 'C' upon restart (as explained here: http://support.apple.com/kb/HT1533]. The CD spun, but except for the noise nothing happened. (I own a Macbook Pro 2.2 GHZ Intel Core i7 (early 2011)).

I've checked the ISO file, it is a Linux boot CD that I suspect is not tuned for Mac hardware. I'd say contact Crucial customer support.

(The guide states:

Firmware version 010G includes improvements which are specific for Windows 8 and new UltraBook systems, although Windows 7 and other operating systems and computer platforms may also see improvements.

so maybe you are not missing much...)

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.