Changes

[[Latin Modern Roman]] for example happens to have over 600 glyphs, so it may be that your favourite glyph (such as <code>udoublegrave</code>) is already there, but you can't access it using standard encodings. In this case you can write your own encoding and support for it. This way takes some more effort and skills than all of the above mentioned solutions and it also takes additional effort if you want to compile the document on another computer. But unless you are using [[XeTeX]], [[Aleph]], ... or any other TeX system which got rid of the 256-glyphs-limit, this is the only proper way if you're opting for high quality.