there are problems accessing USB cdrom during boot. Because of BIOS suport, eCS can use USB cdrom to do initial boot but once eCS drivers load eCS can not see the rest of the cdrom. So you can use USB cdrom instead of diskette images but not to do a complete cdrom install.
I have done eComStation install on Eee PC but have not gotten wired NIC, wireless NIC or sound drivers to work.
Below are some of the steps I used to get the install started:
1. create Linux USB bootable USB key
need one 2GB key OR two 1GB keys OR one 512MB key and USB cdrom
2. zip copy of eComStation cdrom to USB key (2GB key or 2nd 1GB key)
(also put eCS install key on USB)
** step 2 can be skipped if you have USB cdrom **
3. boot linux with USB key
4. delete all partitions on SSD drive (use fdisk or gparted)
** for steps 4 and 5
** depending on the Linux you use
** you might have to add Linux packages
** gparted and mdostools (FAT16 filesystem)
5. create 800MB FAT16 partition at end of SSD drive (use fdisk or gparted)
label partition "ECS_CDRUN"
4. unzip eCS cdrom zip or copy eCS cdrom to "ECS_CDRUN" partition
5. and eCS key to "ECS_CDRUN" partition
6. boot eCS using USB diskette drive or using USB cdrom
"use own boot options"
a. change video to VGA
----- creating Linux bootable USB key -----------------
There are many tutorials on the Internet.
Here are a couple:
Install Pendrive Linux from special bootable CD
http://www.pendrivelinux.com/2007/06/06/pendrivelinux-installation-from-cd/USB Pendrive Linux install from Linux
http://www.pendrivelinux.com/2007/05/16/usb-pendrivelinux-install-tutorial/more
http://pendrivelinux.com/