A CPR JET; DSNDING; OVERSHOT ITS ASSIGNED ALT WHEN DISTR BY PASSING TFC. THE ALT CAPTURE WAS NULLIFIED BY THE CAPT'S MISUSE OF THE ACFT'S HORIZ STABILIZER'S TRIM WHEEL.

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AT APPROX XA40Z NEAR KRENA INTXN ON V100 W OF OBK VOR; I HAD AN ALTDEV. I HAD BEEN CLRED TO DSND TO 11000 FT FROM FL230. I WAS FLYING THE AIRPLANE ON THE AUTOPLT. OUT OF 12000 FT; OUR TCASII GAVE A TA; AN INBOUND B737 INTO ORD. THIS TFC WAS MAINTAINING 10000 FT AND WAS APCHING US ON A 1 O'CLOCK TO 7 O'CLOCK PATH. MY CO-CAPT GOT A VISUAL ON THE TFC AND I ROLLED IN SOME NOSE-UP TRIM TO SLOW OUR VERT CLOSURE WITH THE TFC. THIS WAS MY FIRST MISTAKE. AS THE BOEING PASSED IN FRONT OF US AND OFF OUR L SIDE AND I TOOK MY ATTN OFF THE FLT DIRECTOR AND OBSERVED IT (MISTAKE #2); AS I LOOKED BACK AT THE EFIS I SAW THE FLT DIRECTOR HAD NOT CAPTURED 11000 FT AND WAS CONTINUING OUR DSCNT. I DISENGAGED THE AUTOPLT AND PITCHED UP. WE DSNDED TO ABOUT 10700 FT AND WERE PROBABLY 2 OR 3 MI BEHIND THE B737. AS WE RETURNED TO 11000 FT; CTR ASKED FOR A VERIFICATION OF OUR ALT. THIS WAS VERY EMBARRASSING AND HUMBLING AND COULD HAVE EASILY HAD VERY SERIOUS CONSEQUENCES. IN HINDSIGHT; THERE WERE SEVERAL HUMAN FACTORS. FIRST; WAS MY FAILURE TO USE THE PROPER TECHNIQUE IN APPLYING TRIM WHEN THE AIRPLANE IS BEING FLOWN BY THE FLT DIRECTOR. EVERY AIRPLANE I HAVE FLOWN WILL DISCONNECT ALT CAPTURE IF YOU MANUALLY TRIM WHILE THE FLT DIRECTOR IS TRYING TO CAPTURE AN ALT. WHY I DID THIS AND DIDN'T SEE THE ANNUNCIATION THAT I HAD LOST ALT CAPTURE IS A MYSTERY TO ME. THIS IS ONE 'GOTCHA' THAT WON'T BITE ME IN THE FUTURE. MY SECOND MISTAKE WAS TO AVERT MY ATTN FROM MY AIRPLANE AND A FAILURE TO CLOSELY MONITOR THE AUTOPLT'S FLYING. I VIOLATED THE CARDINAL RULE OF A PLT -- 'FLY YOUR AIRPLANE.' IF I HAD BEEN WATCHING MY INSTS INSTEAD OF THE B737; I WOULD HAVE NOTICED OUR AIRPLANE WAS NOT GOING TO LEVEL OFF AT 11000 FT AND COULD HAVE TAKEN APPROPRIATE AND TIMELY ACTIONS TO DO SO. PERSONALLY; THIS FAILURE IS THE MOST DAMNING AND SHOWS A BREAKDOWN OF PERSONAL DISCIPLINE; SOMETHING I HAVE ALWAYS STRIVED FOR. IT HAS CAUSED A SELF-EXAM OF MY FLYING HABITS; PRIORITIES AND JUDGEMENT. I FEEL PRETTY BADLY ABOUT THIS INCIDENT AND THE AREAS WHERE I WAS DEFICIENT. I PLEDGE TO DO MUCH BETTER IN THE FUTURE.