Hi there,
One answer to your problem might be a Korg Nano Pad.
I looked for one finger chord VST's, utilities and plug ins for ages and almost gave up.
Then I saw the Nano Pad.
The Nano pad allows you to program up to eight notes into one of 16 pads.
So, sixteen chords available, with one finger to play up to eight notes to each chord.
It can be used as a control surface too.
You program 'scenes', which can be loaded into the Nano Controller for each song via a 'Kontrol Editor' in an additional window.
It works independently of Sonar so you set up the scene, tell Sonar it has a controller attached (Midi in-out) and it works as an input device sending midi-in.
Each scene is held on your hard drive so you can make as many as you wish. I name them the same as the song and save them in Cakewalk with my song files so I can find them easily.
Takes a while to set up but is very good once going.
I'm a poor keyboard player, but this has increased my productivity no end.
NB* Took a bit of net searching to find the right driver for my ancient Sonar 2.2!
Here's a link to Korg that might help.
http://www.korg.co.uk/products/software_controllers/nano/sc_nano.asp Good luck and happy Christmas!