I need this feature too. There is a school where with Word they were able to enter 5 special characters often used in their dialect "super easy", while with LiBo is not possible. Even with the ComposeSpecialCharacter plugin is much harder (2 key combination just to trigger the "special character" + 2 to generate the desired one, against 2 in Word).
With KDE I can set a 3 key combo solution, but is not for Windows and they need to be able to work also at home (at school they have LTSP and KDE).
Please implement it :)

Thanks for new idea. I fully agree with it.

Workarounds: 1) try use "USA international" keyboard layout. It contains characters with accents (with right hand Alt)
2) use Basic scripts. Add, for example this script:
sub rim_4
rem ----------------------------------------------------------------------
rem define variables
dim document   as object
dim dispatcher as object
rem ----------------------------------------------------------------------
rem get access to the document
document   = ThisComponent.CurrentController.Frame
dispatcher = createUnoService("com.sun.star.frame.DispatchHelper")

rem ----------------------------------------------------------------------
dim args1(1) as new com.sun.star.beans.PropertyValue
args1(0).Name = "Symbols"
args1(0).Value = "I V "
args1(1).Name = "FontName"
args1(1).Value = "Times New Roman"

dispatcher.executeDispatch(document, ".uno:InsertSymbol", "", 0, args1())


end sub
---------end of citation-----------
Then change line args1(0).Value = "I V " to needed character. Then assign script to needed keyboard shortcut

*** Bug 44629 has been marked as a duplicate of this bug. ***

I am writing mathematic formulas with Writer, without the formula editor, because this is fast in this manner.
I made a lot of macros, and a hotkey for each macros. For example, the integral sign, Greek letters, and by the way, for the charcters of standard notation of English pronouncation.
Microsoft Office Word 2003 can make hotkeys for special characters directly, without macros. It should be good this function in Writer: after choosing the character, a button for choosing the hotkey, and a check box for choosing the insert mode: with the actual font at the cursor at time of inserting, or with a given font, for example, OpenSymbol (the font of the choosed special character).

Microsoft Windows have Alt+Numpad shortcut to input special character, this requiring NumLock turned on.
https://msdn.microsoft.com/en-us/goglobal/bb964658.aspx

But some PCs (such as Lonovo Yoga 13) don’t have NumLock key natively, making this shortcut unnecessary, so in this case allow users to define shortcut keys to input special characters is so useful.

I agree, this would be very useful. It's too much to expect normal users to do this via scripts. In my work I require so many characters not on any keyboard I used to use the Microsoft Custom Keyboard Layout generator - until that starting breaking. Fortunately the Keyboard Layout Manager (commercial unfortunately) works very well instead but it would be better to have this within LO as an easy to use method rather than having people create their own layouts.

One common problem though I've discovered with these is that great care must be taken in implemenation so that if there is a conflict with a system or LO shortcut, the LO shortcut should take precedence. For example, if I put ə onto Alt+E, depending on the scenario, Word used to read this as a hotkey. Or even worse, some shortcut keys like Ctrl+t create a conflict between what Word wants (Increase Indent) and what I want (þ).

So if we do this with LO, at least within LO, if someone goes to the trouble of creating a custom shortcut on the char map, this should over-ride any other shortcut.

*** Bug 157903 has been marked as a duplicate of this bug. ***