Try from a conversion?

[Brandnewtorugby]

Just watched Paul Sackey score a try from a Jonny Wilkinson penalty kick at goal. Got me wondering if you can score a try from a conversion attempt in a similar way like a cross field kick), or is the ball only in play if charged down or comes off a post?

[Raggs]

Conversions aren't open play.  It's just an opportunity to add a couple more points, but the ball is for most intents and purposes, dead.