You can wire the KI kick buttons using the street Fighter CPS1 kick harness it just has to be positioned correctly.
Pinout's are as follows (the relevant pinouts)
KILLER INSTINCT-----------STREET FIGHTER 2
pin7----P1 Low--------------pin3---P1 Low
pin8----P1 Med--------------pin4---P1 Med
pin9----P1 Hard-------------pin5---P1 Hard
Pin10---nc--------------------pin6---nc
Pin11---P2 Low--------------pin7---P2 Low
pin12--- P2 Med-------------pin8---P2 Med
pin13---P2 Hard-------------pin9---P2 Hard
So you line up pin 3 of your Street Fighter 2 kick harness connecter with pin7 on the KI connecter and away you go*.
* assuming you kick buttons on your cabinet are ground without using the Kick harness's