How Do I Lock Specific Cells In Numbers?

I need to lock selected cells on a Numbers work sheet. I know I can lock the whole sheet, but I only want certain cells.
What I have been doing is making a shape the same size as the cells I want to lock, lower the opacity to 0 then lock the shape to cover the cell. It works, but is really clumsy. Any insight would be appreciated.
—–
Ed Weaver