To install custom fonts on android phone make sure you to root your android first to have su on the Droid. You can change the default font in Android by replacing it with any compatible TrueType font (.ttf). Just find the font you like and rename it to DroidSans.ttf and DroidSans-Bold.ttf and then put them into /system/fonts in place of the default files located there.
You have to have ADB functioning OR a recovery image with Nandroid back-up/restore from the recovery menu (SirPsychoS 0.11.0 and above 8 believe).
Follow the steps below to install the Droid Logo fonts (as shown in screenshot above). Download the Droid Logo fonts from here and DroidSans fonts from here. The DroidLogo font is scaled pretty well for the Android OS and displays nicely on both the G1 and the Droid (at least) and has a proper normal and bold version, so will properly display bold text on the phone.
Steps to Install Custom Fonts on rooted Android Device
Step #1 Select a Font for Android device - To properly display font in bold, make sure that a font you want to replace also has a bold version and then replace the normal and bold DroidSans files accordingly. If you make two copies of a single .ttf file and rename them DroidSans.ttf and DroidSans-Bold.ttf it will lose some of the bold formatting.
Step #2 So after you selected the font you want, renamed it to DroidSans.ttf and DroidSans-Bold.ttf
Step #3 Create a folder on your SD card called “n_android_font” (or any other of your choice) and paste both files there.
Step #4 Then create another folder called “o_android_font” (or any other of your choice) so you can have some place to put the original .ttf files so you can restore them later.
Step #5 Rename your fonts file in /system/fonts to DroidSans.bak or similar if you choose, I prefer to store them on the SD card.
Step #6 From an ADB shell:
[shell]
su
mount -o remount /dev/mtdblock4 /system
mount -o remount /dev/mmcblk0 /sdcard
cat /system/fonts/DroidSans.ttf > /sdcard/o_android_font/DroidSans.ttf
cat /system/fonts/DroidSans-Bold.ttf > /sdcard/ o_android_font/DroidSans-Bold.ttf
cat /sdcard/n_android_font/DroidSans.ttf > /system/fonts/DroidSans.ttf
cat /sdcard/ n_android_font/DroidSans-Bold.ttf > /system/fonts/DroidSans-Bold.ttf
mount -o ro,remount /dev/mtdblock4 /system
sync
reboot
[/shell]
Step #7 From Terminal:
[shell]
su
mount -o remount /dev/block/mtdblock4 /system
cat /system/fonts/DroidSans.ttf > /sdcard/o_android_font/DroidSans.ttf
cat /system/fonts/DroidSans-Bold.ttf > /sdcard/o_android_font /DroidSans-Bold.ttf
cat /sdcard/n_android_font/DroidSans.ttf > /system/fonts/DroidSans.ttf
cat /sdcard/n_android_font/DroidSans-Bold.ttf > /system/fonts/DroidSans-Bold.ttf
mount -o ro,remount /dev/block/mtdblock4 /system
sync
reboot
[/shell]
You must change the font only after creating a Nandroid back-up, especially if you doing so from Terminal. You will absolutely have to restore the back-up or adb in to restore the original font if you accidentally delete it or replace it with something incompatible
via[droidforums]
