you need to edit the sentences.txt - its in the valve/sound folder
find the line with the name of the wav that the scientist is supposed to say, it will look some thing like:
// SCIENTIST
SC_OK0 scientist/excellentteam
SC_OK1 scientist/fellowscientist
now, find this line :
SC_ROCKET scientist/c1a4_sci_rocket
you can change c1a4_sci_rocket to iwounded2 or iwoundedbad*
*that name is the wav name with out the .wav
alternatively, you can add a new line to sentences.txt, like so:
SC_WOUNDEDBAD scientist/iwoundedbad
make sure its in somewhere with the other SC_whatever entries
and also be sure to distribute the modified sentences.txt
have i mentioned everything? oh, in the scripted sequence properties make sure you have a ! before the sentence name