Might be a weird thing to suggest, but if you do indeed want to read your data in OOo, why not use XLS or XLSX? Both of those have excellent readers and writers on CPAN, in particular, Spreadsheet::XLSX and Spreadsheet::WriteExcel. You have a way easier time differentiating between numbers and text, and there's no awkward conversions to be done in either Office or OOo/LO.
Update: Excel::Writer::XLSX is another one from the same author as WriteExcel. Spreadsheet::XLSX is the reader for XLSX files. Sorry about the mixup.