I guess you allready seen the tutorials on d3files. There are Q2 style platforms in D3, but I couldn’t get one to work. The brush I used didn’t appear on the map at all, I must be missing something. You can try setting up a door instead of a platform. Though, you might get a situation when a platform will rise while a player just standing next to it. Some dellay will probably help with that.
By the way, are you using an actual .map file of Q2DM1, or are you making it from scratch? I remember using a .bsp->.map converter back in my Q2 mapping days.
And good luck with this project. Edge was a great map, would be nice to see it back in Doom3.