There are two executables available: OnTheFlyWeb and OnTheFlyDocumentSearch. Both are used in the same way; the only difference is where the search engine searches. The Web ending indicates that the search engine searches through a web page, whereas the Document ending shows that the search engine searches through a particular folder.
To run the executables, you have first to install the library. You can find the installation guide here.
$ OnTheFlyWebSearch -p [url] -s [search_term]
Learn more about the available command line options here.