Mark the textpart and then ->Layout->Character->Color
This would change the color of the text.. highlighting would change the color of
the background of the text. Though changing color might do it, it's very
possible that in large docs, changed text color may not get noticed...
then in ert \colorbox{red}{some text}
with a \usepackage{color} in the preamble
or for more than one line
http://www.educat.hu-berlin.de/~voss/lyx/color/color.phtml#paragraph
Herbert
