My suggestion would be to open Excel, record a macro to create and/or position the chart, and then look at the source code of that macro, which will be in VB/VBscript. Then you'll just need to convert that syntax into Perl. Using that method, I can usually figure out how to create the Perl code to do just about anything that I want to do in Excel.

I believe that there at least a few nodes that discusses how to go about doing this process (manually record a macro and convert the VB into Perl). Just do a super search.

Give that a shot. If you get stuck, just come back and ask for help.