You don't install it into X4, you install it in windows -- and then it becomes available in X4 and other programs.

To install it in windows, right click on the TTF file and it will probably offer an install option. If not, then drag it into c:\windows\fonts.

You can also use Bitstream (font program) program that comes with Draw.
Start... Programs... Corel it's listed there.
I've made myself a folder with all the fonts, then you launch Bitstream Font Navigator and you find all your fonts.
Windows complains about more than 1000 fonts being loaded on to it's C/Windows/Fonts.
You can do it!
 

font management is an art of its own.

certainly if you stick with known fonts and consistently
ask people to 'prepare for service bureau' or 'collect for
output' so you have EXACTLY the fonts they used in their
jobs you narrow down problems - even then its not always
foolproof. Also backup a set of fonts you use alot.

using something like Font Navigator (which come with corel)
or the plethora of Font Management software (eg) X-Fonter
you can specifically install fonts into custom directories ideally installing no more fonts other than the vanilla XP (or whichever Windows you are using) fonts in the C:Windows/Fonts
directory. This is the method i use and have few problems.

However i've had no end of trouble on a Windows 98 machine where i have to install via the Start>Settings>Control Panel >Fonts
and then install via File>Install New Font or i end up with disappearing fonts from font lists or worse yet 'invisible' fonts in the jobs using any other method. (IE) Font Navigator.

I hope that helps...and if its a Mac it is a bit different for font management with dfonts, screen fonts or things like people managing to install 5000 fonts on an OSX machine several times giving the dreaded spinning candy of death.