I want ot be able ot have a term open which shows the tail opf /var/log/messages

What I have so far is

alias watchtail='su -c "tail -f -n 3 /var/log/messages"'

SO if i run watchtail
i get
Passwordput in password)
and it work, but I would like if it was able to be run directly from one command (so i can put in my fluxbox menu, if you know what i mean)
Is there a way to pass the root password as a command in this case?..
I'm wondering that it is difficult to do as a security feature, and if so, what would the best way for me to do that?
I guess open a term, and type watchtail and then the password, but i am too lazy

Anyway, if there is a better way, that would be cool, if not, thats cool too.