Actually, it should be near exactly the same as the contact collision in the Dark Invaders example.
if ((MouseX > (dbSpriteX(#)) && (MouseX < (dbSpriteX(#) + dbSpriteWidth(#))) && (MouseY > (dbSpriteY(#)) && (MouseY < (dbSpriteY(#) + dbSpriteHeight(#))))
However, a lazy method I just thought of would be to create a 1x1 pixel sprite that is clear and then update it to the position of the mouse and just use dbSpriteHit() on that sprite.
The problem I can't find in the documentation is how to get the mouse's X,Y position. You can set it with dbPositionMouse() and find out how much it moved with dbMouseMoveX(), Y(), or ? Z()?.