Obtaining stars vector position in relation to the center of the galaxy at a given date

EDIT: It turns out a major problem with galaxy-center-based coordinates is that we don't actually know how far from us the center of the galaxy actually is. According to https://en.wikipedia.org/wiki/Galactic_Center estimates vary between 24,800 and 28,400 light years. You could arbitrarily choose a value, but the results would be off by at least 2,000 light years in some cases.

I was surprised that I couldn't find something like this
online directly. The closest I found is the file
"heasarc_tycho2.tdat.gz" on
http://heasarc.nasa.gov/FTP/heasarc/dbase/dump/

The format is explained on
http://heasarc.nasa.gov/W3Browse/all/tycho2.html and it
includes the galactic latitude and longitude which are
explained here:

https://en.wikipedia.org/wiki/Galactic_coordinate_system

Using this information, you'd still have to compute the
positions yourself, but at least all of the data is there.

Of course, as others have noted, you can take any star
catalog with any set of coordinates and convert it to the
format you need. The catalog I list above just makes it a
little easier, since they're precomputed some of the steps
for you.

As you mention above, SIMBAD also includes galactic
coordinates, but I couldn't find an easy way to download
the entire catalog.