Yup, after pushback is complete, I just use 'callsign xxx, continue taxi', since I made this edit yesterday, and they taxi to the nominated intersection.
If they are on their way to the intersection, and you decide to change it, then giving full new taxi instructions will work also. They stop for a little while, think about it (plan route), then continue taxiing. In this case it would be 'callsign xxx, runway xx (optional @ intersection)
Also if you have already given a pushback clearance, and want to change it directly after pushback (and they have requested taxi clearance), you can do the same as above 'callsign xxx, runway xx (optional @ intersection), and they will taxi immediately without a 'continue taxi' instruction