It's under the Keyboard. It is referred to as an RTC battery. (Real Time Clock)
1) ALL power removed from the laptop. AC adapter (Charger) and Battery.
2) It would be in your best interest to buy, and wear an ESD wrist strap.
(Electro Static Discharge)
Connect the alligator clip to a good ground source.
The price of an ESD wrist strap averages from $3 to $12.
Carried in a multitude of stores.
Example of an ESD wrist strap,http://ultrastatinc.com/ESD_Wrist_Straps.html
[ Your body carries Static electricity.
Static will fry out (Short Circuit) the hardware components inside a computer.
You may not see it, or feel it.
Your computer will. POOF!
I connect to the metal frame of an empty desktop computer case ]
3) Keyboard Removal:
Laptop closed turn the laptop over. There is 1 Philips screw to remove down in the middle of the Battery Compartment, towards the inside edge. (Battery removed)
Turn the laptop over to it's normal position. Open it.
There is a slim strip of plastic that covers screws that hold the Keyboard in place.
The name of it is Keyboard Holder.
It is right above the Keyboard on the LCD screen side, and below the strip of plastic that contains the Power On button, LED lights, and speaker ports.
(This strip of plastic above is part of a cover, that removes when the LCD Display is removed. It isn't an LED/Switch Cover, per se)
Ease your fingertips in-between the latches that hold the Keyboard Holder in place, and the computer, lift up on the Keyboard Holder.
The Keyboard Holder is a slim strip of plastic. Going along it are plastic protrusions, or tabs.
These tabs are on each side of the Keyboard Holder.
Starting from the Left side there are tabs on each side of the Keyboard holder.
Go towards the Right side approximately 2 inches, and there is another set of tabs.
There are 5 sets of tabs.
You need to ease up on the Keyboard Holder by placing your fingertips under it, in-between two sets of those tabs.
The plastic Keyboard Holder will slightly bend, and come up far enough for your fingertips. Then slide your fingertips towards one set of the tabs, and ease up. This part of the Keyboard Holder will pop up.
Keep going towards the next set of tabs, and keep popping the Keyboard Holder up.
Example: Start from the Left side. Come over about two inches from the Left end, ease up on the Keyboard Holder. Slide your fingertips towards the tab set on the Left. Pop the Keyboard Holder up. (The tabs will release) Now go to the right to the next set of tabs.
Once the Keyboard Holder is removed, there are two Philips head screws to remove, that hold the Keyboard in place.
These are at the ends of where the Keyboard Holder was. One screw on each end.
(You'll see plastic tabs coming from the Keyboard where the screws are)
Screws removed ease up on the Front of the Keyboard.
(Front is towards the LCD screen)
Turn the Keyboard over carefully towards you, lay it down on the Palm Rest Cover, (And Touchpad)
(Front of Keyboard comes up, and over towards you)
There will be a flat ribbon cable attached. You shouldn't have to disconnect it, or fully remove the Keyboard in order to access the RTC (CMOS) battery.
The RTC battery is similar to the normal batteries used in a desktop computer, (CR2032), but is smaller in size, and is enclosed in a plastic 'bag'. (Plastic holder)
There are two wires coming from it which end in a male connector. (White)
The male connector plugs into the motherboard of the laptop.
Use your fingernails to ease the male connector out.
This is a link to the Toshiba Satellite Tecra M2 Series Service Manual (Free)http://www.tim.id.au/blog/tims-laptop-service-manuals/#toc-toshiba
Go down to the line that begins with Tecra.
Go across to M2, and click on it.
This is a 16MB PDF file. Takes time for it to download. You won't see anything happening until the file is almost fully downloaded, then the first page pops up.
(Medium speed DSL connection it took almost 2.5 minutes to download. May have to have a talk with my ISPO, lol!)
For questions about the above, or further questions please state in a comment.