The only way to do an actual 'type on'-effect at the moment is doing it through the API (i.e. by writing some software).
However, if the production team realy, realy wants this effect you could create a 'type on'-effect-like animation by covering each line of text by a rectangular mask and animate the masks one by one from left to right revealing the text line by line.
Obviously this is not a real 'type on'-effect, but if you do the animation fast enough most viewers won't see the difference.
#Carbonite