Patrick, though you can't force the player to speak realtime (at least, not with current implimentation of ULX) if you would like to edit what is said.
scroll to the bottom of ulx_fun.lua and look up about 20-30 lines,
find the following exact line
-- Gimp Messages --
there are several 'table.insert( gimp_say,....' lines there.
Add more following same format listed there.