Alright, importing the maps requires you to first extract them from the original game. Thankfully this is a fairly simple process, requiring only one extra utility; RAED.
http://www.cnc-comm.com/community/index ... iew;down=1
You'll need to unzip this into your
original RA directory (not ORA!), and you'll also have to insert an original game CD for it to work.
On starting the program, a list of maps will appear. You'll want to find the ones beginning with SCM, as SCG and SCU are for campaign missions (although these can also be imported, after tweaking of course). Open a map, then immediately save it as an .ini file.
Open the ORA map editor. There's a menu option to import a Red Alert map. Use this, find your recently-saved .ini, and everything should be imported without a problem.