Here is one way to do it: use XeTeX and type UTF-8 into your
Assume that χ ⧐ 0, then \ldots
What I have done here is to use an editor (gedit) which allows me to type and save UTF-8. I've used Character Map in GNOME, which is a program that lets you see each Unicode code point, search for particular code points, and show them in different fonts that are installed on your system. There are similar programs for Mac and Windows, I presume. Once I found the right code point (U+29D0, VERTICAL BAR BESIDE RIGHT TRIANGLE), I copied it to the clipboard and pasted it into gedit. I also copied another character just for fun, as you can see.
xelatex foo.tex on this gives the output (in
You can choose another font – but if the glyphs are missing then you will get blanks instead of the desired characters. The downside is that you can't use the default LaTeX font Computer Modern because it doesn't have the ⧐ character. But with XeTeX, you have all system fonts at your disposal so the problem is now reduced to finding (and possibly installing) a font that you like and that has the right glyphs. Of course, you could change the font for only this one character, possibly defining a new command for it. Then you would just need to select a font where this glyph works well with the Computer Modern glyphs.