No manager panel,
manually edit /service/smtpfront-qmail/rblsmtpd.conf
one dbl (ordb) is already in this file....simply continue adding servers with a '-r' infront of each one. the qoutes will follow the last server.
you can then test your blocking by sending an email to ordb (see ordb faq). Send it from an account on your sme server. you will know within minutes if the block worked. spamhaus.org also has an email test.
good luck,
ryan