You may have a newer or perhaps an older undocumented printer
Why not use SNMP MIB browsing to detect the required queue name?
Here are 2 ways we have confirmed
(I wanted to do this for 2 years now)

Windows 2000/XP
Give your printer an IP address
Ensure you can ping the device from a Windows 2000/XP box
Create a new printer using the standard port monitor
Enter the IP of the printer and click next
If you are lucky, an SNMP poll will the show a queue name you can use
If you are unlucky, 2000/XP will instead find and use raw/port 9100...doh
If you can disable raw/port 9100 and reboot the device you should be able to repeat the process to get the queue name

Freebsd Solaris Linux NetBSD HPUX 10.20 ... probably many others
Net-SNMP is an excellent start http://www.net-snmp.org/
Its command line utilities snmpget and snmpwalk are excellent

I discovered Net-SNMP through mbrowser from http://www.kill-9.org/mbrowse/
"Mbrowse is an SNMP MIB browser based on GTK and net-snmp"
It is a great GUI based SNMP browser based on Net-SNMP

Mbrowse is really easy to install under FreeBSD since it is in the ports directory (FreeBSD rocks)

Before we do anything, I need to explain what the Object Identifier or OID is

Object Identifier (OID)
The hardest part in all of this is the use of the Object Identifier or OID
Each SNMP detail has its own identification name called the OID
You dont have to worry much about this with much MBROWSE or SNMPWALK
However, with SNMPGET, you have to specify the exact OID you are looking for
In playing around with Mbrowse I discovered the LPR Queue name OID's for Canon and EFI devices are different
Canon Controllers LPR Queue name OID        enterprises.1602.1.3.3.1.9.3.0
EFI controllers LPR Queue name OID             enterprises.1602.1.3.3.51.9.1.1.2.IP.1
In the case of the EFI device you also have to replace IP with the TCP/IP address of the printer
So an iR600 with an IP address of 192.168.10.100 would have a LPR Queue name OID of enterprises.1602.1.3.3.51.9.1.1.2.192.168.10.100.1
Dont be scared if this appears to tricky, you can use MBROWSE or SNMPWALK instead

Here is how to use Mbrowse (GUI)
After installed simply put the IP of the printer in the Host name field
Enter the following in the Object Identifier field
Canon Controllers OID        enterprises.1602.1.3.3.1.9.3.0
EFI controllers OID             enterprises.1602.1.3.3.51.9.1.1.2
You should see the queue name in quotes like "lp" or "print_600-605"
A ""  would mean any name

Here is how to use snmpwalk and snmpget on the command line

SNMPWALK
Usage                       snmpwalk -v 1 -c public IP of printer OID
Canon Example        snmpwalk -v 1 -c public 192.168.10.97 enterprises.1602.1.3.3.1.9.3.0
Result                       enterprises.1602.1.3.3.1.9.3.0 = "lp"

EFI Example            snmpwalk -v 1 -c public 192.168.10.100 enterprises.1602.1.3.3.51
Result                       Lots.  You will have to search for it

SNMPWALK has the advantage of not requiring entering the entire OID
Although you may get a large list of returns, its easier than specifying the exact EFI OID

SNMPGET
Usage                      snmpget -c public -v 1 IP of printer OID

Canon Example        snmpget -c public -v 1 192.168.10.97 enterprises.1602.1.3.3.1.9.3.0
Result                       enterprises.1602.1.3.3.1.9.3.0 = "lp"

EFI Example            snmpget -c public -v 1 192.168.10.90 enterprises.1602.1.3.3.51.9.1.1.2.192.168.10.90.1
Result                       enterprises.1602.1.3.3.51.9.1.1.2.192.168.10.90.1 = "print_600-605"

Hope this helps