Go to your xcel file. Paint what you want to bring over. Choose the "copy" command.
Go to your DWG file. Choose "paste special", choose the bottom radio button.
You can either dbl click the spreadsheet from your cad file, or just edit it yourself from the xcel file.
Keep in mind. your copying rows and cols, so if you add a row or col to the spreadsheet, you'll have to redo the process to pick up the new rows and cols