I've been known to throw DD into the bath/shower when this happens as water tends to help her. I have read on the SN boards of 1 DM who has put her DS into the bath fully clothed more than once! (If it works, it works!). The aim being to deal with the short term crisis and then move onto the next stage needed in a calmer mode.
DD also takes melatonin at night to help her relax and get sleepy - she started it when on concerta (long acting Ritalin) but still needs it many nights even though she stopped the concerta 8 months ago.
We used to have a small trampoline, and bouncing on that sometimes helped. She always "thumps" down the stairs - she seems to not even notice that she does it despite all the giving out we do about it, but I know its about seeking sensory input.
We often have things slowly winding down for up to an hour before bedtime - watching a tv programme together and DH or I rubbing her back (almost massage - the light touch seems to help). Often we end up sitting with her once she's in bed and reading, even still, as while she will listen to an audiobook, she also wants company and our voices many nights. But can't fall asleep in silence and music seems to stimulate her rather than help her wind down.
Routine helps - so repetition of "wees, teeth, pyjamas" as the mantra, and keeping to the same routine (in general) for bedtime.
Would he respond to a visual timetable, even just for the bedtime routine?
And absolutely to the keeping calm. It is unbelievably hard to do, and consistently, but it really does help to be calm, non-responsive when she flares up. Sometimes that means giving her space to react and let it out, sometimes that means responding by getting her into the water, or handing her a cup of hot chocolate or something to distract her, or giving a big pressure hug - we don't always get it right (not by a long shot!) but we are getting better at seeing what might work better some nights and not on others. Or spotting the more "stress" days before bedtime, and knowing that we will need to do the relaxing routine before bed tonight, whereas others are fine and she can play outside with her friends or we can do heavy jobs together up until bedtime.