This depends on how well the tile has been stuck to the wall in the first place. If it has a 'solid-bed' of adhesive under it then you a very small chance of managing it - provided you use a very small tungsten or diamond tipped chisel (or, better still, a pointed tile scribe). Take a flask and sandwiches 'cause you'll be there for a long time!
On the other hand, if the tile doesn't have a solid bed of adhesive you have next to no chance or succeeding without breaking it.
In my opinion your best bet for a successful outcome would be to hire a diamond tipped core drill and try it that way.
Firstly you need to drill a small pilot hole in the tile with a normal masonry drill bit and then use the core drill with a pilot drill.
If the core drill doesn't have a pilot drill attached, you'll need to drill a hole in a piece of plywood with the core drill first (don't tell the hire shop people or they may get a bit upset) and then get a couple of people to hold the plywood on the wall with the hole in the correct place and then use the hole in the plywood as a 'steadier' until the core drill have formed its own 'key'. If you don't the core drill will slip all over the place.
The only other option would be for you to drill a series of normal (6mm?) holes around the inner edge of the hole close together. Then, once the centre of the hole has fallen out/been levered out you can clean up the edge with a little chisel or scribe but, again, this does have its dangers.
Or, if the pipe is well out of the way, you could drill the series of holes on the circumference of the pipe hole and hide the chewed up edge with a silicone bead.
Choose your poison!!
Hope this helps.
Regards
Paul Eamonn
