Can't Boot XP - keyboard/mouse drivers missing

Clarifications

Is it USB keyboard/mouse? Either way (assuming it is plugged into a motherboard device) you should be able to reload the motherboard drivers and that should solve the problem.

If you can't get to the install program without the keyboard and mouse, not sure what you can do other than reinstalling the OS.

While it is not your exact situation this article may help (especially the remote registry entry;

http://support.microsoft.com/kb/257729

Another option that may help would be to use the Recovery Console to see if the i8042prt.sys service is set to automatic and not disabled.
One way is to listsvc, I like to just use the Enable command without the startup type;
EX: Enable i8042prt
(should return one of these - SERVICE_BOOT_START, SERVICE_SYSTEM_START, SERVICE_AUTO_START, and SERVICE_DEMAND_START.

Then you would use the;
Enable i8042prt SERVICE_BOOT_START

So i assume you are using Logitech equipment. So far I have never had a problem with Logitech hardware not detecting and autinstalling its own drivers. However if you are not able to use the present keyboard and mouse then try booting up with a dfferent keyboard and mouse plugged in, if you have a PS/2 keyboard it will work 99.999% of the time. then once you are logged in you can try reinstalling the drivers.

Sometimes the remote console will still funtion correctly even though the local keyboard and/or mouse is not working.