Attribute dimension update using groovy

Summary:

I am looking for a solution to update non-HR positions added by a Planner during the budget process. Currently the user has service admin roles and is able to directly update the dimension properties and we would like to stop this going forward. Instead, a planner/user will update attribute values from a form (mix of plain text and smartlist) against shadow Account members and a groovy rule gets kicked off on save. I was able to set this up using saveMember() function but since this is a privileged method, it needs admin privileges. Any thoughts on how we can accomplish