I haven't looked at the Resource Kit scripts recently, however I do know you can specify multiple DNS servers in the networksetup command line (at least in 10.6):
On Feb 23, 2011, at 3:04 PM, Daniel Behan wrote:
networksetup -setdnsservers (interface) 172.16.25.1 8.8.8.8 8.8.4.4
et. al.
