Here are a couple options:
If it really needs to be stored as one field, then you can use jQuery to concatenate and format all the separate inputs. Then set that as the value on single hidden input field named after the Freeform field you want to use to store the data. You would do this on form submit. Easy to do with a little jQuery knowledge (but out of the scope of this site).
If it doesn't matter that it's stored as a single field (ie, the only time the data needs to be viewed as a single block of text is in an email notification or template) then you could just pull all the separate variables together using Freeform tags.