The code linked in reply 8 above should do what you want. Each channel can be individually set to a user defined failsafe value which will be returned on detection of loss of a valid signal. (Alternatively, any channel can be set to use the last good value received.)
(peeking at other thread)
Oh, now that is just sweet, being able to set failsafe per channel in setup()...or not set it!
For a battlebot or something, last good value before you were jammed may be OK.
For an aircraft that may not be good. (Imagines the beginning of an outside loop...)