There's not a 'native' way to do that, but there are a ton of LISP routines that will accomplish that goal. Most likely you'll want to save the XLS file as a text fILE or cvs, and then use a LISP routine to place points or blocks at the coordinates.
If you were to consider third party software (especially if your needs are more than just inserting the points) take a look at the MapWorks Points add-on, which will read the XLS file directly.
Also, Excel is a great tool for preparing AutoCAD SCRipt files. You could use it to create a script file to insert your own point blocks and even populate the attributes. Here is a detailed related example on how to create layers from a spreadsheet.