Unless I am not understanding your intent....
Yes, but...
Index entries are linked to existing topics. If this is a new project, you can import existing topics and the index entries will be imported as well. Similarly, if you are importing a Word document, you have the option to import the index entries.
Importing the index entries without the topics makes little sense because the keywords have to be included (explicitely in the text) or separately as a keyword, linked to the topic. Without the topic, the index entry has no "home".