If I were to start a ToB game, is there any game way of starting a romance with anyone, as opposed to a Console method?

Not officially.

But in the Flirt Packs for Aerie and Jaheira, you can indeed summon them as "my lover" and get the romance going that way. You even get a new conversation along with it.

http://www.forgottenwars.net/npcflirt

(Viconia and Anomen flirt packs coming soon.)

Kelsey-TOB has this feature as well.

http://www.forgottenwars.net/kelsey