vimdiff-like highlighting within the same file?

Hello,

I'm trying to add new features to vim's handling of .po files. How could
I highlight the differences between the current msgid and the previous
one?

#, fuzzy
#| msgid ""
#| "The following disk access storage devices (DASD) are available. Please "
#| "select each device you want to use one at a time."
msgid ""
"The following direct access storage devices (DASD) are available. Please "
"select each device you want to use one at a time."
msgstr ""
"Următoarele Dispozitive de stocare cu acces la disc (DASD) sunt disponibile. "
"Vă rugăm să alegeți pe rând fiecare dispozitiv pe care doriți să-l folosiți."

I'd be grateful for any hints or RTFM pointing to the right FM, because
I have no idea where to start.

Regards,
Andrei
--
If you can't explain it simply, you don't understand it well enough.
(Albert Einstein)