My only recommendation for priming is to take about 230 mL (or you can use a 240 - 250 mL measuring cup, but 230 is about the right ratio, and one cup is about 238 mL) of the dextrose, add about the twice the amount of water, and microwave it. Stir after every 2 minutes, and add water if it's boiling and you still have undissolved sugar. Let it cool a little, and add it to the carboy. Shake slightly, and bottle.
I've done this to the Mexican Cervesa mixture, and it works like a charm -- actually, I've done this to demijohns of this product, and all the bottles are carbonated.