How to read and modify existing Stylesheed

Hello,
i use a excel file as a template for a dataexport. Is there a way to read tge ecisting Stylesheed an modify it bevor i write the file back?
Thanx
i use a excel file as a template for a dataexport. Is there a way to read tge ecisting Stylesheed an modify it bevor i write the file back?
Thanx