I wanted to try and "slow down" a track over time.

I found that if I used this older-looking plugin called Pitch Shifter and manually moved the top parameter (called "shift" I think), it would simulate that effect by gradually lowering the pitch of the audio.  It's one of the plugins included with Sonar.  And it has the old-school plain-Jane interface.

Now the issue was that this older plugin could not be automated.

Is there a similar plugin or process for doing this so I can automate it?

Not sure how long you are thinking the time it slows is - but I have had lot's of fun with this and it's free too!

Ha! I've used this before on a whole mix. It actually worked really well :) I forgot who made it and what it was called. Thanks!