You can buy a phantom power supply, but I don't know if they have one that is battery operated for "field recording." The one I had plugs into the wall and it has XLR input and output. You plug your mic into the input with an XLR cable of course. Then you plug the output of the phantom power supply into the multi-track using an XLR cable with a quarter inch adapter on the end that goes into the multi-track (or you can buy a cable that has XLR on one end and quarter inch on the other.
I have a recording box (external soundcard) type thing, and it actually has a switch that gives phantom power
Take a look at the Edirol UA-25. you can plaug it into your pc and record shit, PLUS it has phantom power for you to plug in your hardcore condenser mics.. mine has both 24v and 48v