I use audio snap to do this. Sometimes I change a Jingle from straight to swung for a completely different feel... original songs too. You'll want to make sure your transient markers are in the right place first. You can then use Quantize to swing the audio, OR manually move the Transients by hand. I've done both for different situations. Typically you'll be swinging the eighth notes OR the sixteenth notes depending on the song you're working on. If it's eighth note swing, you'll be moving the notes on the 'AND's of the beat (one AND two AND three AND four AND. If it's sixteenth note swing you'll move the notes or audio that's on the 'EE' and 'UH's of the beat. (one EE and UH two EE and UH three EE and UH four EE and UH.
In Sonar (Cakewalk) Swing @ 66% is a 'normal' swing (quater note , eighth note in a tripulet time). 50% is straight (no swing). Beyond 66% is Over swung( useful in EDM or Jazz swing). In between 50% and 66% you'll find an in between feel. (think Jerry Lee lewis or the song 'Run Run Rudolph') Below 50% is a negative swing also good for a change in 'Feel'. Probably not what you're going for here though.
Not that hard to do, you will need to have some patience and diligence.