That was it. I set *acpi=1 and now the usb mouse works.  Thank you! 

    On Friday, September 21, 2018, 7:37:38 AM CDT, Tobias Heinicke <theinicke@bss-wf.de> wrote:  
 
 Do you have ACPI turned on (e.g. *acpi=1 in your plan9.ini), because I
noticed an issue with USB mouse sometimes not being detected if they
were plugged in during boot (detaching and attaching again after 9front
is up solves the issue [dev/usbevent then has an attach line for the
mouse while previously there was not one {no detach logged}]).

I only noticed this issue with ACPI turned on, but I have not been able
to track down the exact reason yet (thus I refrained from writing a mail
to the ML).

--
Tobias Heinicke

On 09/21/2018 06:11 AM, G B wrote:
> I asked previously about disabling the touchpad for a Lenovo laptop, but I've changed things around.  I put FreeBSD on the Lenovo N580 and 9front on the Thinkpad T60.
>  
> The good news is I have WiFi working with 9front on the T60, but I can't get a USB mouse to work.  However, if I run Plan 9 from Bell Labs on the T60 a USB mouse works.
>  
> How can I get the USB mouse working?
>