@stiger Look at this post:
https://forum.acronis.com/forum/acronis-true-image-home-forum-older-versions/pxe-boot-possible
I’m copy/pasting the important part in case the resource goes away:
After the installation of Acronis on your Desktop DON’T create an ISO.
Start a creation of an USB stick. Then on the USB Stick you’ll find the files
dat3.dat / dat2.dat.
The file dat3.dat ist the kernel.dat.
File dat2.dat ist the ramdisk.dat
So you could rename them and copy it to you’re tftp.
The menu should so look something like:
SAY 02 Acronis true Image 2010 Home
LABEL 02
kernel acronis/kernel.dat
append initrd=/acronis/ramdisk.dat vga=791 root=/dev/ram0 quiet