It should be possible Greg as the non-turbo and SD Xantia used a push clutch. I reckon you might need to swap the flywheel and certainly you'd need to swap the clutch release arm in the bellhousing.
If it will give you what you want though is another matter entirely. I find a good 1.9TD pull clutch is an absolute delight and as light as a feather and not really any harder to swap than a conventional push clutch given all the other issues surrounding a xantia clutch swap
My experience with push clutches is that they wear a groove on the tips of the diaphragm springs over time through the release bearing constantly bearing on them. This makes for a jerky, snatchy clutch long before the plate wears out and this is worse to me than a pull clutch getting heavier over time. I've swapped several for this reason and found a good plate each time. That is annoying.
One thing to always do when swapping clutches, be it push or pull, is to always replace the nylon release arm bushes. New ones make a heck of a difference to the lightness and smooth operation of the clutch.