If your .3ds model was exported from 3DS Max, I know the following will work to correct the orientation. You would do this immediately after loading your object. This may work for .3ds files exported from other modeling programs as well (I am pretty sure it works for .3ds files exported by Google Sketchup as well). If not, you might have to play around with the angles to get your model in the correct orientation:
newObject.rotateX( (float) Math.PI / 2 );
newObject.rotateY( (float) Math.PI );
newObject.rotateZ( (float) Math.PI );
newObject.rotateMesh();
newObject.setRotationMatrix( new Matrix() );
The above assumes there is only one sub-object in the model, or that the objects were all merged into one. If you are loading your model with the "children of a dummy-object" method, then you would use this on the array returned by the Loader class:
for( int x = 0; x < objs.length; x++ )
{
objs[x].rotateX( (float) Math.PI / 2 );
objs[x].rotateY( (float) Math.PI );
objs[x].rotateZ( (float) Math.PI );
objs[x].rotateMesh();
objs[x].setRotationMatrix( new Matrix() );
}
If this doesn't work, let me know what modeling program you are using, and I'll do a little research to see if I can figure out what angle changes you need to make.