Ah, here we go, ill post this in the tut section for future reference.
In HMT save the meta of ui/hud/hud_icon_messages (in the ustr taglist).
Open the meta in HexEditor
Scroll down the code until you bump into the vehicle names.
Select each letter one by one and change it in the string box. (under the binary boxes).
Then press return
Only one letter between each dot (in the ASCII window)
The new name cannot be more letetrs than the existing one.
If your new name is less than that, fill in the extra letters with spaces.
Inject the meta into ui/hud/hud_icon_messages in HMT.
Now enjoy your new vehicle name!