You can generate cell names A1 and B2 from integer coordinates using the PHPExcel function, the name of which I do not currently remember (will be added when it is detected) and simply concatenate the names using ":" as the glue symbol and use the same code as and now.
EDIT
The function used to create the column name by its coordinate,
PHPExcel_Cell::stringFromColumnIndex($colIndex)
Gedrox
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