Trying to change my mouse from ps/2 to usb I've seen no modules are found.
Here's the output:

[root@localhost giulio]# mousedrake
FATAL: Module usb_uhci not found.
FATAL: Module usb_uhci not found.
FATAL: Module usb_uhci not found.
FATAL: Module usb_uhci not found.
FATAL: Module usb_uhci not found.
FATAL: Module usb_uhci not found.
FATAL: Module ehci_hcd not found.
FATAL: Module ehci_hcd not found.
FATAL: Module hid not found.
FATAL: Error running install command for hid
insmod'ing module hid failed at /usr/lib/libDrakX/modules.pm line 61.

I'M COMPLETELY SURE I have *statically* compiled these modules in the kernel.

Also:

[root@localhost giulio]# lsusb
[root@localhost giulio]# lsmod
Module Size Used by
joydev 8448 0
eth1394 18120 0
ohci1394 32132 0

Why it loaded ohci instead of uhci? Uhci is the one I selected during configuration.
See it:

#
# USB Host Controller Drivers
#
CONFIG_USB_EHCI_HCD=y
# CONFIG_USB_EHCI_SPLIT_ISO is not set
# CONFIG_USB_EHCI_ROOT_HUB_TT is not set
# CONFIG_USB_OHCI_HCD is not set
CONFIG_USB_UHCI_HCD=y

I Don't understand.

You seem to need ohci support. This is one of the 2 possible USB 1.1 bus drivers, depending on your USB host chip. And the hardware dictactes which driver we should use, not the other way around...
ehci is the (unique) driver for USB 2.0.

And at the occasion, activate hid support for your mouse.

When I look at your output, I would say, you are not booting the kernel you just compiled: could it be the case?

Nope...it was the kernel I had just compiled....that sunds strange to me in fact.
Now I'm compiling this damn'kernel for the 93975934th time since sunday.... :-(