jessie install cd no network

[Javier Marcon <javiermarcon@gmail.com>]

Hello, I downloaded the Jessie install cd and added a preseed file to
automatically install some packages, but running the install cd does not
recognize the realtek network cards, telling me that no network hardware
was detected.

If I install it in a Virtualbox machine (with a phisical disk mapped)
and then I boot with that disk, the network cards work perfectly.

the cards I have are:

javier@javier-System-Product-Name:~$ lspci | grep -i ethernet
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL-8100/8101L/8139 PCI Fast Ethernet Adapter (rev 10)

How can I make the debian installer to automatically boot these modules
in the kernel?

Thanks,

Javier.