Yes, please dont jump on me, I tried the search function but couldnt find anything that would help me.

I want to use the Font "Segoe UI" in my Setup Billboard. And I've read that I must register that font somehow before it can be displayed during the installation.

Can anyone tell me how I do that?

Thanks in advance and best regards
Mike

First, you'll need to have the two TTF files in <windows folder>\fonts before first reboot. Three solutions :
A (beginner level)> copy SegoeUI.ttf and SegoeUIBold.ttf in $oem$\$$\fonts, and be sure to have OemPreinstall=Yes in winnt.sif
B (i hate cows level)> copy SegoeUI.ttf to I386, cab it, copy SegoeUIBold.ttf to I386, rename to SegoeUIB.ttf and cab it. Then add the two files in DosNet.inf, and in TxtSetUP.sif (renaming back SegoeUIB.ttf to SegoeUIBold.ttf via txtsetup.sif)
C (i format my hd every two hours level)> use a pyron's modded setup.exe, and a custom presetup.cmd to copy the .ttf files

Second, to register the fonts you need to add a line for each in your hives' AddReg sections :

(HIVESYS.INF and HIVESFT.INF are the best choices IMHO)

++

Great! Many thanks to you!