Kupo has some great advice, so I'm just going to provide a helpful resource that I cam across. It is a
tutorial on doing lineart in opencanvas (it's free if you'd like to
try it) and discusses doing lineart with a mouse, so that might be helpful to you as well.
3nodding Tutorial Exerpt
Inking with Mouse:
Zoom in as big as you can and ink using slow strokes using water colour or pen tool.
I hope that helps a little. ^_^