http://ivan.sourceforge.net/ivanmap/IvanMap.exe
Sorry that there is no Unix version, and there probably won't be a port as I can't even compile the source any more.
Note that I had to go to program properties and set it to start in full screen to make it work under WinXP. Otherwise only half of the screen was shown. Another way is to start command prompt, go to full screen by pressing Alt+Enter and starting the exe there.
Probably the best way to use this is to draw a room, then press Alt+Enter to go to window mode and use the window edit options to select and copy a portion of the screen to the script file. For instance this room took twenty seconds to make with this method:
#########+############ #......#.......#.....# #......#.......#.....# #......#.......#.....+ #......#.......#.....# #......#..############ ########..#..........# #......#..#####......# #......#......#......# #......#......#......# #......#####..#......# #..........#..#......# #..........#..#......# ######################
Hope it shows correctly in your browser.