Depends on what you mean by "air assault infantry". Technically you can do it with leg infantry loaded onto transport VTOLs. Since the definition I found was light infantry supported by transport helicopters.
If you don't want to slow down, jump infantry and jump capable battle armor can leap out and land (terrain depending, don't do this over water) on the underlying hex.
I'm not sure which book, but one has rules for ziplining from choppers.