I learned to write over more years than I care to count because I just never stopped writing, in one form or another. A school, of any type, is not really going to teach someone who isn't ready to learn. The secret is simply to write a LOT and to read a LOT.
And I still stink at writing combat.
But, if anyone is interested in this idea, I'm open to suggestions. If anyone wants to approach me privately about how to improve their writing then I'll pass on the suggestions I've received over years of trying to learn to write well.
If, however, you're looking for some sort of directed theme writing . . . that could actually be fun. There's a thread on another forum where a music video from YouTube is posted and the writers all attempt to write a scene inspired by the song. Something along those lines could be rather fun indeed.