The hubs that were built to take alloys have studs with either a '-' or a triangle stamped on their outer ends. I don't know what makes them different, whether it's their length or strength so I can't comment on whether it is safe to fit alloys to hubs not intended for them, but "I have been told" that if you remove the spring washers form the drive member securing boots that they do fit, however you will have the end of the halfshagft sticking out through the alloy.
If the halfshaft doesn't interfer with the alloy then either youhave non-LR alloys and I can offer no further advice or you have axles with alloy compatible hubs.
HOWEVER, only use alloys intended for the DEFENDER e.g. BOOST alloys if you have a 110 or 130, otherwise you are breaking the law, technically, as the other LR alloys are not weight-rated to carry the back axle of a longer Defender.