PCheese enlightens us with his discovery:
Once your level is made, make a new RGB or grayscale image that with dimensions (x-1) pixels by (y-1) pixels (where x is the width of your level in tiles and y is the height of your level in tiles). Next, set the pencil color to one of the following. RGB: (115, 115, 115). HSB: (0?, 0%, 45%). (although any color other than black or white seems to work). Now draw in the xichrons, where every pixel is a xichron centered on the corresponding tile. Note that the upper left pixel of your image corresponds to tile (2, 2), so everything is slightly offset down and right. Then select and copy the entire image and choose "Paste PICT as Xichron Map" from the Edit menu in the MASCOT editor.
Black and white pixels are ignored. Therefore, you could create the FG tilemap of your level in black (ground) and white (air), paste it into the editor as a FG tilemap, then add gray xichron pixels. Then paste it again as a xichron map, and only the gray pixels will show up as xichrons. You can therefore use the black and white ground image as a guide you can 'paint' directly onto.
Note: be careful if you have a lot of grey in your image, or you might get hundreds of dialogs saying you can't have more than 512 sprites per level. I can't find a color that makes a red xichron. I've checked about 70% of the colors already.
(This message has been edited by spamguy (edited 07-02-2002).)