Harm was made so that you can only target yourself or your party with the spell from a sequencer staff, so this is possible.
Just make Shapechange Self only and let it be cast on Sequencer Staffs. Seems silly to ban shape change from sequencer staves, especially since it's not on the wiki ban list and I had to find out from other players it was banned after failing to add it to a staff.
It's not like Shapechange is gamebreakingly powerful.