modifing existing Excel cells using perl in Unix possible?

Hi,
I have been trying WriteExcel, and ParseExcel both to modify the
existing excel cell data, but I am not able to get through. I would
really appreciate it if some one can help me out. I have been looking
for examples for this, and a few examples showed how you can add data
to the existing spread***, but so far i could not find anything on
modifying existing cell data. Any pointers?
Thanks in advance,
dd007

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