hi, i've tried it with yew branch that ive had knocking about for a few months . i 'defrost' for 5 minutes, remove, allow to cool, repeat. til i get no more steam. be warned though it does just start to split in the ends so i leave the blank an inch or so oversize so i can cut the ends off.
I've made a lot of pens and have needed to dry some blanks in a rush. I didn't have much success with the microwave, they were dry but very brittle but it could just have been the species I was using.
What I have done in the past is to cut the blank over length, drill it undersize and mount it between centres, deadcentre in the headstock and turn it down, bit like rough out a wet bowl and then leaving it for a couple of days. Job done.
Best way of all is time, while you are trying to speed up a few for immediate use, throw half a dozen other well figured pieces into a suitable open tray or box and keep topping up the stash whenever you have some off-cuts big enough (don't cut too small if green, some wet wood can move a great deal whilst drying) given a few months/years you will have that many options to use you will be able to sort through them and discard those that seemed a good idea at the time and find something to meet your current wants without having to worry about how dry they are. I find slow air dried is usualy less brittle and easier to turn.