Have you tried Google Autodraw?
This morning I came across Google AutoDraw - it seems really neat at first glance, though it couldn't recognise my drawing of a stick man. A coffee mug and a pencil yielded better results. A quick transparent fill using Snagit and I had me a shape that I could change the colour and position of any way I liked. Custom shapes in Storyline will yield much more complex graphics, of course, but autodraw might do the job if you need a quick icon or symbol? What do you think?