I want to have voice input in messaging. However, in the settings I don't seem to be able to get to the correct setup.
The only way I know is through apps...
The app Better Keyboard will give you the option to use voice input on anything that makes the keyboard pop up.
Specifically for SMS, 2 apps.. SMS Popup and Hancent both can do voice to text for just text messages.
BK is $2 or $3.. SMS Popup and Hancent are free... I use BK and SMS Popup for additional functionality.