you need 4 fontfiles:
the regular one
the bold one
the italic one
the bold/italic one
then you need to edit the font.xml file with the names of your fonts
the fontengine.xml contains the default font size for small medium and large. you can edit it if you want to make them smaller or bigger
the xml files can be edited with notepad or similar
BEWARE: do not use a font.xml file designed for other phones then a2 DB3210 as other phones (like db2020) have a completely different layout in font.xml and using it will cause the phone to not boot anymore!!!
i will add the default font.xml and fontengine.xml files for w995 so you can use that one for editing.