If the method you'd come up originally doesn't work fine with non "square" sheets then what would you recommend.
Furthermore, I can't seem to be able to make your original last row/column script work. The dos prompt tells me the following :

Bareword "xlPrevious" not allowed while "strict subs" in use at D:\sou
+rce\readExcel.pm line 30.
Bareword "xlByRows" not allowed while "strict subs" in use at D:\sourc
+e\readExcel.pm line 30.
Bareword "xlPrevious" not allowed while "strict subs" in use at D:\sou
+rce\readExcel.pm line 33.
Bareword "xlByColumns" not allowed while "strict subs" in use at D:\so
+urce\readExcel.pm line 33.
[download]

What should I do ?

edit (broquaint): changed <pre> to <code> tags