ModKeys blog post is up;
So now it's clear how modifiers work it is also clear that Mouse + Cut/Copy/Paste has been partially solved by ModKeys. The left hand can chord Ctrl with the pinky and adjacent finger on the z and x keys.
The index and middle fingers are free to hit the c and v keys.
The remaining problem is "x". It is already in use for the Ctrl chord so you can't execute a cut unless you let go of the mouse and return the right hand to the keyboard and execute the Ctrl chord on the right side thus "unmasking" the x on the left side.
The solution I'd propose is similar to shift-ahead. If the Ctrl chord is pressed (&released) then sustain it and wait for the next keypress. If that keypress is x then execute Ctrl-X.
It makes cutting into a two press action rather than a rollover but I think it would be livable