One person who knows about writing good MASH scripts is Ken Levine. He is a writer, producer and director on shows like MASH, Cheers, Frasier and many more.
His blog at kenlevine.blogspot.com is a daily read. He has a lot of insights on television and the entertainment business. And he has a great podcast too.
I'd forgotten until recently that back in 2008 he even wrote an entire column answering a question I wrote.