Currently there's no feature of this sort in OJS, although the subject has come up once or twice. The problem is that you'd lose much of the functionality that makes OJS useful -- for example, searching, subscription and access control, etc.
On the other hand, there are many free utilities that will get you half-way there (such as wget and htget on Linux, running in mirror mode) and that, in combination with some manual HTML work, should get you what you're looking for. Unfortunately, it'll take quite a bit of fine-tuning by hand.
Open Journal Systems Team