You can open the wordlist and select the book filter for the book or books that you want to count. If you use a priority you should be able to select down to a particular chapter or chapters. With the range you can select specific verses.
Then export the list to an xml file using the menu > export to xml
Open that file in Excel and allow Excel to create an xml table. This will put the data into columns (one of which is Count)
Use =sum(xx:yy) to generate a sum of all the words in the selected text.