
The player can walk through the mirror so I suggest putting walls inside the mirror. The Glyph locations for the mirror are hard-coded into the game and cannot be changed. Here are the levels and coordinates:
Fire and Home Glyphs: Level 57, X=12, Y=29
Ice Glyph: Level 66, X=28, Y=24
Floing Glyph: Level 56, X=47, Y=54
Friend Glyph: Level 61, X=4, Y=24
How to set up the Glyphs:
When you select the Custom item, keep right clicking the Fn option until you see "Glyph" come up. After that, the texture number that the custom item uses will decide where the mirror leads to.
Texture 16 will always act like the Fire Glyph.
Texture 17 will always act like the Ice Glyph.
Texture 18 will always act like the Floing Glyph.
Texture 19 will always act like the Friend Glyph.
Texture 20 will always act like the Home Glyph.
EDIT: Forgot to mention that in order for the glyphs to take effect when used, there cannot be more than 4 tiles between the player and the front of the mirror.