I have sketched out the last four entries in my Mirror Universes series. The process for each one is basically the same.
First, I write out the 'parallel techniques' I can think of for the instruments I am using in the piece. For example, MU3 involves vibraphone and trombone. Both can do pitch bends (the vibraphone is obviously more limited there). Both can have brighter timbres if played at the node or with a mute. Once I have a list of these type of ideas, I determine how many of each there will be (generally 3-4 per effect and 4-6 for "normal" melodic figures).
Then comes the pencil sketch. These are very rough and I write them quickly. It's almost an improvisation.
Once I have the pencil sketch, I sit on it for a few days, then start putting it in Sibelius, with corrections and additions.
Once they are all in Sibelius, I plan to send Caleb the scores as .pdfs for suggestions and revisions. Tentative plan is to record these sometime around the winter holidays.