Hi,
Pls maintain the data sequence like sap ME51N in excel sheet and copy all line items and then open ME51N and click on customize local layout->clipboard and then do paste button.So,whatever you have copied in excel sheet data ,they will be copied into ME51N.
Note:1. Pls keep cursor in field item before you click on button paste.
2.The above way will work for header level only not for item level.
BR's,
KNR