From the documentation, you can access the table contents as follows:
Access by row and column
$data->val($row,$col)
You can also use column names rather than numbers:
$data->val(10,'AZ')
Access data on a different sheet:
$data->val($row,$col,$sheet_index)
I haven't spent much time (yet) exploring the different possibilities but you should be able to:
* loop through the cells, modify the data if necessary and save it to mysql.
* Copy the content to another table; modify the content as necessary in that table; display that table and then call my desktop_write utility to save it.
I haven't done the full end-to-end version of this but it shouldn't be difficult.