I use Resource Hacker - I believe it can be found in the granary.
Whether you use pebbles or resource hacker, you shouldn't find the process difficult. Simply search the unit name you want to change and then edit away!
Each string has an ID number, with each range appropriate to the following (these are approximate ranges):
5000's - Name of unit
6000's - Scroll-over command button text (train villager etc)
16,000's - Hotkey/shortcut key
23,000 - 24,000's - Lookup name used by the EMPIRES.HLP file
39,000's - Popup help box text for unit
40,000's - Popup help box text for unit train command
[This message has been edited by Rasteve (edited 10-13-2009 @ 07:11 AM).]