Cutting ceramic floor tiles in place

["Bill Gilroy" <wmgilroy@gmail.com>]

I am installing a pocket door into one of my rooms and the wall that it is
going into is 1/2 the width of a 2x4 wall.  It was made by turning the 2x4
90 degrees making the wall stud 1.5 inches thick.  I need to replace the 1.5"
sill and replace it with a 2x4 sill and a standard 2x4 framing.   This means
that I will have to cut back the ceramic floor tiles about 2 inches.  This
tile is set on a piece of gray cement board.  Any ideas what is the best way
to cut this tile without doing any damage to the rest of the floor.

Thanks,

Bill