I built my CLFS-Embedded. It boots and all works. However, now I want to configure the network. I'm using linux-libre, and the firmware for my WNA1100 is proprietary, so the only chance I have, since I do not want wired networks, is how network works in my host Parabola GNU/Linux system: tethering the net from my Galaxy S. Now, in Parabola it's just connect the phone, enable tethering, # dhcpcd usb0 and it works.
However, in CLFS, that's not possible. # udhcpc -i usb0 returns an interface does not exist error. How can I make the USB tethering work on my CLFS-Embedded system?
As a side note: could anyone suggest me a good package manager for this system?

There's a whole menu on usb networking in the kernel config, including something to handle arm embedded. You probably want stuff out of that. As we don't have much detail, I can't be sure.

I followed these instructions, but still it does not detect the phone.

find your kernel config. If you're on a distro kernel, it's usually /boot/config-version. Run

grep USB_NET /path/tp/kernel_config and post the output in code tags (#)