As a general rule you should enable ssh key exchange on your cvs repository and then the question becomes moot.
From your development machine:

ssh-keygen -t dsa
(accept the default for all queries)

$ cat ~/.ssh/id_dsa.pub | ssh ${repository_host} "mkdir -p .ssh ; cat 
+>> .ssh/authorized_keys"
(enter your password)

$ ssh ${repository_host}echo
(answer "yes")

$ ssh ${repository_host} echo
(Nothing should happen, you should just get your prompt back)
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You need to set the following environment variables (put them in your .profile or .bashrc) before you can run any cvs command:

$ export CVS_RSH=ssh
$ export CVSROOT=${username}@${repositry_host}:/path/to/cvsroot/
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Hope that helps