To configure an HP jetdirect card starting with discovering what the ip address of the printer is set to
(at the printer control panel on the top right of the printer cabinet) 
start with the procedure to obtain the internal tcp/ip configuration of the printer and do a self test:
(this worked on a laserjet 4m)
1. press the online button once and the light will go out indicating off line. 
2. press the menu button (the buttons will softly click each time you press them) until you get TEST MENU
3. press the item button until you get SELF TEST
4. press the enter button ( you will see 05 SELF TEST in the
   window). After about 10 seconds or so the printer will
   print out a page of info. In this info will be the 
   ip address of the card. On mine it is on the right
   side in the middle of the page. Then go to 
   the printer configuration on your GNU/Linux workstation printing configuration 
   menu and set it for jetdirect. If you follow the directions there, you should
   have no trouble with the configuration. After entering the ip address
   and the name of the printer it worked first time for me. (A word of caution:
   unless you have information to the contrary from your sys admin, 
   use a private ip address otherwise your printer may
   be accessable to the entire internet.)
   You can also configure the ip address from the 
   printer as described in PART B which follows.

Now, to configure TCP/IP ( the ip address of the printer ) at the printer control panel :
(The star means selected or entered; without the star
   the choice you make is not saved; press enter to get the star and save your choice)
1. press the offline button
2. press the menu button until you see AUX IO MENU (on this test unit it took 8 pushes - your unit may vary)
3. press the item button until you see CFG NETWORK = NO
4. press the + button to get CFG NETWORK = YES
5. press the enter button to get 	CFG NETWORK = YES *(this saves your choice)
6. press the item button to get CFG TCP/IP = NO
7. press the + button to get CFG TCP/IP = YES
8. press the enter button to get CFG TCP/IP = YES *(this saves your choice)
9. press the item button to get IP BYTE 1 = 0
   (This could be any number between 0 and 255, 
    pressing plus increases the number in steps of
    1 hold the plus button down to automatically 
    advance the numbers. Hold down the shift button
    red letters to make numbers go backwards this is 
    where you set the ip address of the printer. This
    number will be the first number in your address
    like this: 192.168.1.1, this will be the 192 part.
    before you press the the item button again to get to
    IP BYTE 2 = 0 (or what ever number it is set to) be
    sure you have pressed enter to change the entry and save it.
10. press the item button to get IP BYTE 2 = 0
11. press the item button to get IP BYTE 3 = 0
12. press the itme button to get IP BYTE 4 = 0
13. As you continue to press the item button you will
    get something like this SM BYTE =  or LS BYTE = 
    or GW BYTE =  these stand for Subnet Mask, GateWay
    SysLoGserver. You may want to set these too. Again,
    be sure to press enter to get the * which means you
    have saved the value. You can always test your 
    entry procedure by using the test menu above
    that will tell you if you successfully changed the
    ip address, subnet mask, and defalult gateway.
    Both these methods worked for me. I hope they work
    for you. If you are using dhcp there is a menu for
    that too. I believe it is bootp.
14. Press the online button to exit and print; or to ping the ip address that you set.
    I would recommend pinging the printer at its new ip address to be certain that 
    there is communication to and from the printer. For example, if the ip address you
    set the printer to is 192.168.1.5; to do this type (at the command prompt):
    ping 192.168.1.5 (with a space between the word ping and 192.168.1.5).
    You should get something that looks like this:
    PING 192.168.1.5 (192.168.1.5) 56(84) bytes of data.
64 bytes from 192.168.1.5: icmp_seq=0 ttl=60 time=5.24 ms
64 bytes from 192.168.1.5: icmp_seq=1 ttl=60 time=2.38 ms>

64 bytes from 192.168.1.5: icmp_seq=2 ttl=60 time=2.13 ms

--- 192.168.1.43 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 2.134/3.256/5.248/1.413 ms, pipe 2  

the "3 packets transmitted, 3 recieved, 0% packet loss" tells you 
that the printer's communication system is working.

It is also possible to telnet into the printer. For example if the address of the printer
is 192.168.1.5 ( you would obtain this from the self test described above in PART A; 
you would type telnet 192.168.1.5 and then press enter on your keyboard (there is a space between
the word telnet and the 192.168.1.5) This will connect your computer with the printer's telnet menu. 
This menu has a help section that is easy to follow.