Man if you have to use a microwave then this method is probably the way to go... copied and pasted from elsewhere..
get an ordinary microwaveable plastic container. put a dry piece of kitchen towel, maybe torn in half, on the bottom of the container, then chop a few buds to a smallish size so it dries out quicker, therfore keeping more un-evaporated thc in the spliff, and then place the buds on the paper towel. Next, wet two paper kitchen towels and dry them out so they are not dripping, but slightly wet. it helps if they are attached when wetting them! now poke a hole or two in the paper towels which you have placed over the buds, and put the lid about 3/4 the way on.
Put in the microwave and 'cook' for one minute.
take everything out and dry any moisture that will be in the container.
get the other, dry torn half of the paper towel and put the drier but still moist buds on it.
make sure the paper towels are still wet and do the same thing as many times as you need to until you are happy.