A KING AIR B200 PLT LANDED ON THE WRONG RWY AFTER BOTCHING A GPS NDB APCH.

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THE WX AT ALN WAS MARGINAL VMC; SO I DECIDED TO FILE FOR 3 ILS APCHS TO RWY 29. THE LOC WAS OTS; SO I REQUESTED THE NDB 29. THIS IS ALSO A GPS APCH. I SET UP THE NAV EQUIP TO DO THE NDB AND TO MONITOR IT ON THE GPS. I DECIDED TO USE THE GPS AS THE PRIMARY REF FOR THE APCH. IT IS A KING KLN90B WHICH IS CERTIFIED FOR INST APCHS. I; HOWEVER; SET IT UP TO INTERCEPT AT QUNIE; THE INITIAL APCH FIX. APCH VECTORED ME TO 5 MI OUTSIDE ALPOS; THE FINAL APCH FIX. WHILE TRYING TO ADJUST THE GPS FOR THE CHANGE; I FAILED TO MONITOR THE RMI AND PASSED THROUGH THE FINAL APCH COURSE. WHILE CORRECTING; I GAINED CONTACT WITH THE ARPT AND LANDED ON RWY 35. I HAD BEEN CLRED FOR THE OPTION. TWR MADE NO COMMENT. NO OTHER ACFT WERE TAKING OFF OR LNDG. I REALIZED MY ERROR AND MENTIONED IT TO THE TWR CTLR. HE WAS MOST COURTEOUS. HE MENTIONED THAT CLRED FOR THE OPTION DOES NOT MEAN CLRED TO CIRCLE FOR LNDG. I DID ANOTHER TKOF AND LNDG VFR AND QUIT FOR THE DAY BECAUSE OF APCHING TSTMS. THE KEY TO THE PROB HERE WAS NOT KNOWING WELL ENOUGH THE USE OF THE NEW GPS WE HAVE INSTALLED. I SHOULD HAVE ASKED THE CTLR TO VECTOR ME OUTSIDE QUNIE OR COULD HAVE EASILY REVERTED TO THE RMI FOR THE APCH BUT INCORRECTLY CHOSE TO REESTABLISH THE PROGRAM IN THE GPS TO INTERCEPT JUST OUTSIDE ALPOS. RESETTING THE GPS WOULD PROBABLY HAVE BEEN A VIABLE ALTERNATIVE WERE I MORE FAMILIAR WITH IT. GETTING BEHIND IN THE APCH LED TO THE MISTAKE OF LNDG ON RWY 35. THE SOLUTION TO AVOID A RECURRENCE IS TO REMEMBER TO AVOID USING NEW EQUIP IN THOSE CIRCUMSTANCES REQUIRING QUICK ADAPTATION TO CHANGES UNTIL I AM THOROUGHLY FAMILIAR WITH THE EQUIP. IT WOULD ALSO BE WELL TO PRACTICE WITH NEW EQUIP IN MORE FAVORABLE WX CONDITIONS.