Here is a link to the netweaver help: http://help.sap.com/saphelp_nw73/helpdata/en/48/abdd83c3333205e10000000a42189c/content.htm
Your best bet is to do a small export of the data you want to migrate to get the format you need and then write a small script or program to convert your excel into the right text format. I have used a blt in the past and dumped the text right onto the tracer.
