Well, you don't need to get inside the cab....all you do is take a properly fitting screwdriver to the grille screws and turn the screwdriver anti-clockwise to remove them. You're not likely to shear the screws when you're taking them out, the only thing to be aware of is not to be too ham fisted and chew up the screw head, that's why it's essential to make sure the screwdriver is a correct fit for the screwhead.
Same for the drivers, just remove the screws and ease them out. The speaker driver will have a cork or rubberised gasket between the speaker frame and the cab to prevent air leaks, this gasket is under constant compression when the speakers are screwed into the cab and sometimes they can stick to the baffle a bit and need a bit of gentle persuasion with a flat blade (a blunt filler knife or even one of your dinner knives)...just run this gently round the driver between the gasket and baffle to break any stiction and ease the driver out. There will be speaker wiring attached to the terminals on the back of the speaker, either with terminal screws, spade connectors or even soldered (so don't just rip the speaker out), but you shouldn't have to undo these wires, you should be able to turn the driver enough with the wires attached to see the back of the voice coil enough to see any identifying labels. Unless you need to verify that all the drivers are the same, you should only need to pull one driver, have a quick look and put it all back together.
Honestly, it's almost easier to do than describe, but if you can't trust yourself to undo a few screws without wrecking anything, probably best left to somebody else.
