Underlay map image in QwtPlot

I've been using Qwt for a while to do relatively simple plotting, but I haven't used many of the more intricate features. I'm currently working on quick turn-around project which requires me to plot lat-lng points on top of a map image. I've got everything working except the map image underlay, and I'm not really sure how to approach it.

Basically, I'll have a set of image files and lat,lng points corresponding to the corners of those files. I'd like to add these images to the plot at the appropriate positions. I'm assuming I'll need to use QwtPlotRasterItem, but I don't really know where to start other than that. Can someone point me in the right direction?

Thank you.