Laptops :: HP Omnibook 800 CT

I've installed 4.4.10 as an HDD install using the xfbdev video mode and it works well except the built-in mouse doesn't work, the cursor flies all over the place. I've added a USB card and USB scroll-wheel mouse and that works fine. The built-in mouse is PS/2 and that's what I selected in xconfig.
I'd like to use the built-in mouse as it saves having to carry another mouse around.
BTW, this laptop has a P166-MMX processor and 32MB RAM but it works really well under DSL, even web browsing using Dillo is quick