First of all, it is illegal to do so. Secondly, the only way is to disconect the speedo sender, which obviously also stops the speedo so you wont know how fast you are travelling, but that will stop the odometer.
If you are talking about the trip odometer push the button in and hold it for a couple seconds. It will reset. If you are talking about the constant odometer, there is no way to stop it, unless you disconnect it from the front left wheel well. By the way, that is illegal.
yes
In the gas tank. I have 2001 Echo.
2001 Toyota Echo doesn't have a timing belt.
http://pdftown.com/2000-2002-Toyota-Echo-Service-Manual.html
http://www.carspace.com/guides/Toyota-Echo-How-to-change-oil
3.5 Liters
timing chain.
32 PSI
see link
i have a 2001 and it gets about 39-42 mpg
go to dealer