alternative to drilling the wall to fit a toilet overflow

[Crock]

Hi.

I am fitting a new flush-fit toilet but don't want to drill through the external wall (which is tile-hung) to fit the overflow pipe. Is there an alternative?
I am thinking of fitting it to the soil pipe, or the sink waste, but am not sure if this is in accordance with the regulations

your help and guidance would be greatly appreciated

kind regards

Crock

 

[Northern Scum]

Many modern cisterns have an internal overflow built into the flush mechanism. Are you sure you need to drill anything? If so, what about changing the flush mech to an internal overflow type.