PS2 -> USB magic

[Nicolas Turro]

Hello,

on my laptop (compaq armada m300), i used to plug an usb mouse,
and it was 'seen' as a ps2 mouse by Xfree, without any usb module loading 
(kernel 2.2.18, with custom configure options)

root@polaire# ls -l /dev/mouse /dev/psmouse
lrwxrwxrwx   1 root     root           12 Jun 25 15:27 /dev/mouse -> 
/dev/psmouse
crw-rw-rw-   1 root     sys       10,   1 Jun 25 15:27 /dev/psmouse

and :
Section "InputDevice"
    Identifier  "Mouse1"
    Driver      "mouse"
    Option      "Device"        "/dev/mouse"
    Option      "Protocol"      "PS/2"
    Option      "Emulate3Buttons"
EndSection

In my XF86Config ...
It was kinda magic.... 

Anyway, i compiled a 2.4.17 kernel (with more or less the same configure 
options, but it was a pain for usb), and now the same 'magic' doesn't work....
I must use usbcore, hid, mousedev, uhci modules in order to use my usb 
mouse...

Can someone explain me how it worked in 2.2.18 without those modules,
and is it possible to make the same magic work in 2.4.17 ?

Nicolas