i have seen lantana as tall as i am (6'+) but can't say which cultivar it was(old homesite, maybe just a pass-along plant). the only one i grow is a trailer w/ bright yellow flowers.
as far as training into a standard, i am sure you could do it as you described but it seems to me that it would be necessary to start over each growing season. do the branches not get killed to the ground each winter where you live?
except for the trailing types, i think they grow naturally as multi-stemmed shrubs rather than single-trunked or tree-like.

my lantana is about 3 or 4 years old and around 5-6 feet tall. it dies back in the winter and puts back out from the root not the dry stem, so i am not sure how you'd grow it as a shrub tree. maybe its a different lantana or just requires a whole lot of attention.