A PA31 PLT ALLOWED HIS ACFT TO DRIFT PAST THE ACTIVE RWY HOLD SHORT LINE AND ENTERED THE ACTIVE RWY.

Narrative

AFTER A 9.5 HR WAIT FOR PAX AT ZZZ1; WE PICKED UP OUR IFR CLRNC TO ZZZ2. WE WERE CLRED TO TXWY C SHORT OF RWY 11 TO EVENTUALLY TAXI TO RWY 16 FOR AN IFR DEP. UPON REACHING RWY 11 WE NOTICED THAT THE DEPS FOR RWY 16 (IFR) WERE SIGNIFICANTLY BACKED UP. WE ASKED FOR AND RECEIVED A VFR DEP 'CLRED INTO CLASS B' AIRSPACE UP TO OR BELOW 2000 FT. RWY HDG; SQUAWK THE SAME AND FREQ THE SAME. I INADVERTENTLY CONSIDERED THIS TKOF CLRNC AND PROCEEDED PAST THE HOLD SHORT LINE. BEFORE ENTERING ONTO THE ACTUAL RWY; TWR REQUESTED AN IMMEDIATE CROSS AND 180 DEGS TO HOLD SHORT ON THE OTHER SIDE. WHILE WAITING FOR TKOF CLRNC ON RWY 11 THE TWR CLRED US INTO POS AND HOLD ON RWY 16 AND ASKED FOR CONFIRMATION THAT WE WERE #1. MY COPLT RESPONDED 'WE WERE' AND ACKNOWLEDGED CLRNC. I IMMEDIATELY CORRECTED HIM BY TELLING THE CTLR WE WERE HOLDING SHORT OF RWY 11 ON TXWY C. MY COPLT ONLY HAS 260 TOTAL HRS AND WAS UNABLE TO HANDLE THE CHANGE FROM IFR TO VFR RADIO COM. THEREFORE I DID AND IN THE CONFUSING PROCESS THEREAFTER I MADE THE MISTAKE OF ALLOWING THE ACFT TO DRIFT PAST THE HOLD SHORT LINE.