You'll have to remove the radio. I think the center panel may just pull
out, but I can't remember for certain. Check around the ashtray for
screws. Also check to see if the trim on top of the console is in your
way. I don't think it is on the XG, but I'm having trouble visualizing
the interior. If the center dash trim panel is in two pieces, you'll
probably have to remove the lower first and, if you need to remove the
upper, check for two screws at the bottom of the upper panel. Once the
necessary trim panels are out of the way, there are four screws holding in
the radio.
A way to rosy picture. There's a real good reason car radio
installation places are doing so well - it's because as cars have
gotten smaller it has become exceedingly difficult to do the
removal/installs yourself.
Can you do it? Almost certainly. Do you have the tools? Maybe,
maybe not. Most cars don't use regular slotted or phillips screws
anymore; for the most part they use Torx head type screws, meaning
you'll be buying tools for this one-time use. My experience is these
smaller cars is that you end up having to rip out half the dash to get
to the radio, and it almost always takes john q. public three times as
long to do this as a pro-installer.
Save yourself a headache, the cost of tools you'll likely never use
again and scraped knucles. Have an installer help you out.