Get or hire a core drill and a meaty SDS drill. Use the core drill on drill only, don't use the hammer action. It will take some time. If the wall is random rubble then it's not as bad as a solid stone all the way. It once took me 3 hours to go through a single solid stone 3' thick!  

I assume we're talking about diamond core drillls here?

You'll need extension pieces as well in order to get through a 2 foot thick wall.

Always drill a big pilot hole first as this does two things:

1) Allows the core drill to centre for initial starting (once started by about 25mm then remove the core drill centre guide)

2) If the core drill gets stuck (and it will!) you can tap it out through the back of the pilot hole using a long steel bar.

I have found that using big diamond core drills on damp walls can cause jamming as the 'dust' becomes a stiff paste and wedges everything tight in the wall.  To avoid this I run a 'slow' hosepipe onto the cut and this seems to wash out the debris as you drill and stops jamming.

Just beware of water + leccy drill............  

Agree with stoday on this.

Best and quickest is to remove the stones and re-cement them back in after the pipes in and connected

The wall is 2ft thick not each rock.

The most likely build is with a facing stone inside and out with loose rubble infill, this falls behind the core as you're drilling and invariably you end up making a larger hole to recover the core bit anyway.

As I said removing the rocks usually means about a 12" hole which can be made good using the existing rocks after the pipe is installed.

Tried both ways and I still prefer my way.

If I had a 2ft rock in my case I would rest it as well  

if its solid stone right thru, then the diamond core bit is the way to go, i had to drill one as an apprentice in a school for a new toilet conversion. was a complete bastard, but if you get a decent core drill and let it do the work without "forcing" it through then it won't be too much bother, my guess is that since this post is a month after the original question, the jobs done already, so how about an update...

btk

[quote author=sparxxxx  link=1128720668/0#10 date=1132005412]He followed scruffs advise and his house fell down. he therefore has other things on his mind.
[/quote]

Most of these old stone buildings including mine, are dry stone wall then pointed with cement, the middle was filled with all the loose rubbish.

When you drill through the first stone about 200mm average all the small stuff fall back in the hole and blocks the drill bit.

Done it, seen it done and we all got the T shirts