Your office comp should have all the data of IP's and possibly GATEWAYS within your LAN system.
If your using a windows system you should check out NETWORK in your CONTROL PANEL, and look up TCP/IP for your LAN card.
Once you click that and look, you should find a bunch of TAB's, and perhaps open to IP address.
In IP address, you should find the IP number assigned to that machine and the subnetmask.
Now you could clone that IP address, but it would mean your office machine won't be able to connect while your connecting.
what you really need to do is assign an IP within the ZONE RANGE and keep to the same SUBNET MASK.
so if your company machine says:
IP: 169.254.0.32
SubMask: 255.255.255.0
You should try finding out what other IPs are in your network (keep the subnet mask).
Don't forget to note your offices machine of DNS, GATEWAY and WINS. they too will help you know how your system is set. Infact if your lucky you might find that you get a dynamically assigned IP if the IP ADDRESS tab was empty.
You could try from your office machine a PING to IP numbers within your RANGE, to try and find an empty one.
just open a dos box, or use RUN from Start bar, and PING 169.254.0.43 etc change the last number to check for other numbers on the network)
If you find a machine, it will get a response from the ping, if not it will timeout.
There is possibly a way of writing a BATCH script for running a multiple ping throughout the address range. (but that takes a little time and perseverance to set up)
Best option:
If your really crafty why not ask your Boss, or better still the Tech guy that has to run round and keep track of the computers. If he knows that you want to connect to the network, he's more likely to set it up for you than have you accidentally do something to insecure it.
Edit:
Nearly forgot, don't forget to lookup the Network Neighbourhood name, as if your system doesn't have the same network name it won't show up properly or not at all.