Adding -Rt0 to server_args

[fairvegas]

I'm trying to add -Rt0 to the beginning of my server_args following the activation of sbl-xbl.spamhaus.org in my MAPS:

In the past, I've added -Rt0 to my /etc/xinetd.d/smtp_psa file by running the following command line:
sed -i 's/args\ \ \ \ \ =\ \/var/args\ =\ -Rt0 \/var/' /etc/xinetd.d/smtp_psa

But since adding sbl-xbl.spamhaus.org in my MAPS, it eliminates the previously added -Rt0 and gives me the following new smtp_psa server_args line:
server_args = /usr/sbin/rblsmtpd -r sbl-xbl.spamhaus.org /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true

Therefore, running the previous working command no longer adds -Rt0 to my smtp_psa file:
sed -i 's/args\ \ \ \ \ =\ \/var/args\ =\ -Rt0 \/var/' /etc/xinetd.d/smtp_psa

How should the above shown command line be modified so that it will work under my new MAPS addition in my server_args?

Any help is greatly appreciated!