Haha, well maybe it's a good idea to share what i found on how to draw sprites from an atlas.
I looked through the source and search around for somehat similar problems i encounterd and basically this is what you need to do:
call atlas to get a textureregion2d, call that one with Bounds to get a rectangle as source, crate a destination rectangle with that regions sizes, draw it with the regions texture like so:
TextureRegion2D region = atlas.GetRegion(regionid);
Rectangle sourceRectangle = region.Bounds;
Rectangle destinationRectangle = new Rectangle(position, region.Width, region.Height);
spriteBatch.Draw(region.Texture, destinationRectangle, sourceRectangle, Color.White);
Before all this you have to create a atlas from texturepacker and load it of course.
The documentation on MGE is till a bit unfinished.