jQuery Grid Plugin - jqGrid

I'm having some issues getting some cells (in cellEdit mode) to be non-editable even though the column is set to editable. 

I've tried many ways, like beforeEditCell, formatters, etc. None seem to work.

The closest I've got is by setting a formatter to the column that I'd like to be editable and then using setCell to set the 'not-editable-cell' class. Snippet below. The first time you click the cell, it unfortunately goes into edit mode, but if you click elsewhere and try to re-edit the cell, it's successfully uneditable. Any suggestions?

function noEditFormatter(cellValue, options, rowObject) {

if (cellValue == 'test')

jQuery("#grid").jqGrid('setCell', options.rowId, 'ColName', '', 'not-editable-cell');

return cellValue;

}

Edit: if I put the above code into beforeEditCell, it successfully stops the cell from being edited but in turn 'freezes' the grid. You can no longer select any other cell.