I've done it ... easiest way is save the bi* uncompressed, set value you want to edit to a unique number say 999, 1000 etc. and then go at it using a hex editing program, search for the unit name and then the value. This also works to edit the cost to research a tech. What I have not been able to edit up is the A/D values of units .. tried but they stay at 1000 in game, i.e. when look at the unit after editing the value displayed is still 1000.
What I think is that 1000 is a programmed display limit, but since cost/tech is in turns to get it is harder to have 1000 occur. Just a guess at this point. Oh also when hex edit the cost over 1000 (say to 2500) the value may not be exact based on game diff (i think).