How to get the chainsaw on Mt. Erebus?

Where do I collect this dildo?

According to the Doomwiki entry, the platform starts at the lower height, and rises up if you visit the small structure with the teleporter next to it. Checking linedef/sector tags in an editor pretty much confirms it. Thus, you should grab the chainsaw as soon as you arrive at the area.

This is one of those levels I still find new shit in after all these years. It's a crazy map.

Making threads is always ok.

Wow, I didn't know that. Another place where the original game can screw you and make you miss something entirely. My first instinct when I teleport there is to jump over the chainsaw platform and later over the teleport box as it's much lower anyway.

I knew about the chainsaw and how to get it back in the childhood, but I didn't know then about exit to secret level and what the secret level was.
And by the way, when I first read xeepeep post, I assumed he was referring to the official way to get to secret level, because rocketting yourself is indeed the intended way to do it (although it is possible to do it with straferunning instead). Then I reread the topic title, looked at the picture and was confused, since you don't rocket yourself upwards in vanilla/chocolate. The advice would make sense to me in Gzdoom with rocket jumping enabled. There are also crazies that make/play maps designed around rocket jumping in Doom.

Also, in regards to wiki, I often would look up article on pwad maps on it (for secrets or some kind of write-up about map's history), only to find "it's a stub" notice. Perhaps some OCD-affected individual could go and write stuff on a wiki for every map he plays? That would be a freaky, but amazing way to contribute to community.