Corporate jet Captain reported receiving a low altitude alert from ATC on approach to CVO airport; citing autoflight mode confusion as contributing.

Narrative

After being put on a 200 heading and cleared approach for the RNAV (GPS) Rwy 17 at Corvallis (CVO) airport; I became overly focused on selecting the next altitude (2900) and did not notice I was going through final approach course. I thought I had pressed the NAV button; but was mistaken and I was still in heading mode. Cascade Approach called out a low altitude alert and I turned off autopilot; pulled up; and turned left back to intercept course.I have thought through this and have tried to come up with a technique to keep me from channelizing attention during a critical phase of flight. After thinking about it; my mantra during vectors to final and on final approach will be 'CAMP' for the following:C - CourseA - AltitudeM - Mode (Autopilot mode)P - Push to activate next mode/confirm activationAlso when hearing 'cleared final approach' I will ensure NAV mode is pushed and confirmed activated.I am just trying to apply methods to trap errors that might result in channelized attention and to ensure a continuous cross-check of all parameters.