Read the original dwg.
Read the excel. Create a dummy object for each excel layer wihich is to become a acad layer. (You cannot create a layer with no object)
Write all to a dwg.
Thanks for the answer gio. I'm new to this kind of problems in FME, and I'm not sure that I understand what you mean. Do you mean that I have to create a dummy geometry and add to each attribute feature in the Excel-file? I've tried to use Creator and created a dummy polygon, but I don't know how to add that one instance of the polygon to each feature from Excel. I can't use FeatureMerger for example, since there are no attributes to join.
And to create a layer of each row in Excel, do I take the attribute value from Excel and transfer to the attribute fme_feature_type before writing it all to the new dwg?
Hi again. I solved it myself, thank you.