B737 HAD RWY INCURSION AT SNA.

Narrative

VERY SHORT TAXI FROM GATE TO RWYS 19 AT SNA. GND INSTRUCTED TO HOLD SHORT LIMA; WHICH IS STANDARD. OVER TO TWR FREQ; STARTING TAXI CHKLIST; WHEN TWR INTERRUPTS WITH AN 'ARE YOU READING FOR TKOF?' THE FLT ATTENDANTS WERE DONE; SO WE SAID YES; AND CONTINUED THE TAXI CHKLIST. TWR AGAIN INTERRUPTS WITH A VERY NONSTANDARD CLRNC FOR SNA 'TURN L ON TXWY L AND HOLD SHORT RWY 19L.' THIS PUTS JETBLAST INTO GATE (THE ACR -- THEY DON'T LIKE IT). WE ACKNOWLEDGED AND FINISHED TAXI CHK. FO IS LOOKING AT CHART AS CAPT (ME) TAXIES ONTO RWY 19L. AS I'M XING THE HOLD LINE (HABITS); I LOOKED ON FINAL. THERE WAS A CESSNA ON 1 1/2 MI FINAL. TWR SAW THE INFRINGEMENT AND SENT THE CESSNA AROUND; SCOLDING US FOR NOT HOLDING SHORT; AND CLRED US FOR TKOF RWY 19R. 3 FACTORS STRIKE ME: 1) THE FO WAS CONSISTENTLY WEAK THROUGHOUT THE TRIP; AND I SHOULD HAVE BEEN MORE ALERT TO COMPENSATE. 2) HABITS: BAD -- TAXIING LIKE WE USUALLY DO; CLRING FINAL WHEN XING. 3) WE SHOULDN'T HAVE SAID WE WERE READY. I NEED TO BE A BETTER 'NO' PERSON.