Alright. I think I figured it out.
You have to be using goldwave to do this.
Make a new sound and set it's hz to 11025. I know, low quality, but the effect only works in 11025 and all the voice files in freespace are at this level of quality.
Record yourself and mechanize it by ten. Then extend it's pitch to 120 and preserve tempo. You have to do this in order to get the right distortion of the sound.
Then lower it's pitch to 60% without preserving tempo. Before you do that though, look at the bottom of goldwave and it should tell you the length of the sound. Remember that. After you do the pitch thing, go to timewarp and click the length option and similarity. Type in that number I told you to remember.
Next, go to the euqalizer and put in something that looks like this:

After that you can either play around with the equalizer again or bandpass/stop.
-J.P.