I'd like to hear your reason for using a scheduling tool outside of the Blue Prism Schedular - so we can potentially feed it into our future enhancments. Something to remember is the BP built in scheduler utilizes Resource Pools which gives you a certain level of DR (if one resource goes down another available one is automatically used instead).
I guess you could use any scheduler you want - before the built in solution we used to use windows schedular to kick off sessions - using some of the command line options available in the product. That was a very poor solution (no pools, no ability to automatically start next task once previous one had finished, etc)