Leif, are they points or areal features?
If they are points, it is quite easy:
Produce a GPX file containing them as waypoints, then simply display via our "Define View/GPX" function, or create a Favorites file and display them via Favorites. Look at existing files of both types to see how they need to be formatted. You can produce your file from the location data you have using any spreadsheet application and a bit of string manipulation.
If you want to display areal features, you will have to go more complex ways, like creating a sqlite tile map in something like MobileAtlasCreator and using it as overlay in Osmand (via the Online maps,/ Overlay feature), or creating your own obf vector map using OsmandMapCreator.
Best, Hardy