Just re-read the thread, normally the new bush should be the same shape as the original bushes and go under the existing clamps. Have a look for images of the standard ARB bushes and that should identify if you are using the correct ones.
I have Eibach ARB front & Rear on my Mk4.
Assuming your kit is similar the rear beam ARB bushes are more Triangular with rounded top. the wide flat side is designed to sit on the flat metal of the beam and has a channelled saddle that fits over the bush. the channel lips are to hold the clamps in the correct position. The clamps are also really awkward to fit with the beam mounted. Hope my description makes sense and is of help.
This is a Mk4 install, not my own, very similar to Mk3 -

If you are still struggling, can you post up an image of your kit?