Help with Sliding Maps

[mido]

Hello modding experts, I need some help with creating slide out maps with shipping routes and minefields as they were available in SH3. Please tell me where to start. I have my maps ready but need to convert them into the right format and put them in the game so that they "slide" on top of the nav-map.

If they are ready and work fine I will make them available for everybody.

Thanks in advance