I just tried redirecting a file containing only a carriage return into the command but it doesn't work, i'm sure that would work with a dos batchfile. :-/
Edit: Ah never mind, me being dumb, I should of looked at the man pages first. There are options for the smbmount command that allow you to specify login details.
smbmount //192.168.0.8/Volume_1 ~/NAS -o password=""
Still, i'd be interested to know if there is a script solution if anyone knows.