(I have also done the same for Ireland. I work on a version of Denmark and south Sweden.)
First I find the area I want to map on Google Maps (or any other map). I zoom to the level I like. 10-20 towns (or places) in the area is about right. Make a screenshot of this.
I use a transparent subsector map that I have made using quickhex.
I use a good image editor that can handle layers. (I use GIMP, which is free.) Then I open my screenshot and place the transparent map on top of it as a layer. (I can move it a bit until I am happy where the towns are in the subsector.) This is what it could look like.
Continue reading Subsector from a Map