From:  Frenchy Pilou (PILOU)
5233.2 In reply to 5233.1 
I am not sure of what do you do want! :)
This ? The block killed ? ...
For this I have "projected" to the closest point the red curve to the wall surface on the other side,
Copy move the wall part
draw some lines between the new curve and existing volume, make a volume with some sweeps and make a boolean Diff

EDITED: 3 Jul 2012 by PILOU