I love burritos, but whenever I buy frozen ones they never turn out that good. They get really hard when I microwave them. I've heard if you wrap them in a damp paper towel that they cook better, but have yet to try this.
What brand and flavors do you normally get?
You know those Compleats meal containers? The green ones are two layer devices where you boil the noodles by pouring water in the lower part of the container and letting steam rise through the perforated second layer. Buy one of these, eat it, wash out the container, put some water in the bottom, put your burrito on the top, and pop that baby in the microwave. The steam will keep your burrito from drying out.
As for taste, you'll just have to experiment with sauces that you can put into little containers for convenience.