A few quick notes, although I should emphasize that every child is different and has different learning preferences.
With low working memory and processing, I would make sure that most information was presented in formats that allowed the child to easily refer back to it and that did not require extensive note-taking during instruction. Mastery should not be demonstrated based on timed drills or other formats requiring quick response time. Extended time on tests should be considered.
If the low processing score is reflecting poor motor skills, getting appropriate OT and allowing keyboarding for tests and written assignments are both things to consider.
Evaluating the child for problems with hearing, vision, attention, and auditory and visual processing might also be in order, if it hasn't been done already. (Hearing and vision screenings at school or pediatricians' offices, or ordinary eye exams don't count.)
