I've heard that a good way to defeat a lot of keyloggers is to type in a bunch of garbage, then, highlight and delete the parts you don't use. Example:

Say the password was: 3ct0

You could type in 3658li
Then, highlight everything after the 3, and hit backspace.
Next, type in a4c0et
Highlight the a and 4 and hit backspace. Then, highlight the 0et and hit backspace.
Then, type in 576t0kjle
Highlight the stuff before, hit backspace. Highlight the stuff after the t0 and hit backspace.

Most keyloggers will see that you typed in a bunch of characters and that you hit the backspace key. Some keyloggers, (not any free ones that i've seen, but possibly commercial ones) will log the mouse actions too. But, unless it logs everything (including the point the mouse is at, and all the other events), you're pretty safe using this method.

Other than that, if you are allowed to use some type of diskette or CD, store a file with the password in it, then c/p to the password box.

Of course, that won't work if the logging software cuts a copy to the HD for later inspection or if it just watches what goes through the clipboard. Maybe a combination of this method with the CD and the above method would work well.