Whole-note tremolo beams

[Leo Correia de Verdier]

Dear list!

I’m working on a piece with a lot of whole note tremolos and was wondering if 
any of you have a nice workaround for the beams (issues 318 and 704). I would 
like them slanted (with the same slope as a regular beam), centered between the 
noteheads and avoiding accidentals on the second note column, but if you have 
code producing any of these results it would be welcome. Harm’s code from this 
tread does unfortunately not seem to work any longer 
http://lilypond.1069038.n5.nabble.com/Tremolos-between-two-whole-notes-tt57577.html#a57580
 . I’ll start hacking something together, but if any of you already have 
invented this wheel it would be nice not to reinvent it.

Thanks a lot!
/Leo