Looks like you've managed to work most of this out without me sticking my oar in last night!
For the 'stock', it's mainly flavour you want, not liquid... so i think that the demi glace sounds like it would work, as would the paste stuff that Melissa suggested. Not too sure about reducing down regular chicken stock... my experience with that is that it just evaporates, rather than thickening. I wouldn't put wine in it, but that's just my own personal preference... I never cook with wine. I just don't see the value in wasting the wine when i can't really taste it in the food. Maybe my palate isn't refined enough!
I assume Mort was joking about the refried beans, but for clarity... it's just regular white beans or pinto beans you want for this... including the thickened 'juice' from the tin (as long as its not got sugar in it).