If you can create a high-quality color BMP image, there is a plugin which will import it for you. For example, here’s the letter “B” imported from a 893 x 943 image (the higher the resolution, the better the result):
You can download the plugin from here:
https://sites.google.com/site/spirixcode/code/spirix_bmp_tracer.rbz
Once installed, it should show up on the Extensions menu as “BMP Tracer”.