Hi Joseph,
While just about anything is possible with enough elbow grease, in this case it won't be easy. Even if you could launch an external application from within a web-browser (probably using a custom URL scheme), getting it to communicate back to QATrack+ would be another challenge to overcome. If you have an external application you want to use to enter data into QATrack+, then you'll likely either need to use QATrack+'s API to upload the data, or, have your external program output a file which you can then upload and parse in an upload test.
Randy