As Buellers, we can agree that Xb's should have come with a voltmeter or at least battery light. The mod is simple and been done enough times to not re-hash it here.
But I'm going to anyway :angel:
The process is the same, take apart the dash, dremel clearance, install gauge...
Attachment 13307
Attachment 13308
Attachment 13309
BUT a long time ago on e-bay I found these:
Attachment 13310
a Temp gauge!