Steering Wheel Control

Hi Folks, I'm struggling with a project and I'm hoping someone smarter than me can be of some assistance. I am trying to re-purpose some unused button on the wiper and indicator stalk and use them for steering wheel controls for my Kenwood head unit. I have purchased a Maestro SW control unit to be used to manage the signals. Here's the current situation.

There are 2 buttons on one stalk and 3 on the other. 2 button on each stalk merely create a connection when depressed (momentary buttons). In other words, they are feed with a +ve supply and that connection is made when the button is pressed so that the +ve signal is output to another wire. The 3rd button on one of the stalks works in the opposite fashion. It has a constant +ve signal which is interrupted when the button is pressed (I believe its a cruise control cutton - cancel likely). So, my problems are as such.

1) I can add different resistors inline with each output wire to differentiate the signals from each button press. Tech support suggested a "resistor ladder" though and being a neophyte, I'm not sure how I'd go about this (I can solder stuff though), how exactly a ladder works (in layman's terms) and why this would be better than simply adding different resistors in line with each wire.

2) What am I going to do about this third button? I suppose I could wire in a relay to reverse the operation of the button but this is more hassle than I'd like to go through if I can avoid it. Would the use of the ladder allow me to keep the function on this button (breaks connection, not makes connection) in some way?

Many thanks for any suggestions offered!