I have LWAMI 3.11, but I must have missed the part about the ACTUV platforms. The manual is pretty big, you know.
The thing here is, I don't think that they are playable platforms. LWAMI adds many new platforms to the game, but (with one or two exceptions) none of these are playable. Basically, if you design a new mission you will be able to implement these new platforms but they will be AI and non-driveable.
Besides, why would you want to drive anything other than a 688i, Akula, or Kilo?
I hope that clears it up for you. Hopefully someone else will come along shortly (within a few weeks, perhaps) who can chime in about some other details I might have missed.
If you are looking for a mod that adds additional
playable platforms you should check out the threads about the AlfaTau mod in the mods forum. I believe they are calling it AlfaTau nowadays, but I could be wrong about that. I don't know much about this mod as I haven't tried it, but it might be more along the lines of what you are looking for.