after some more searching, I found the linux side of things has been moved into the kernel tree.
Compiling from the kernel git:
$ usbip version
usbip (usbip-utils 1.1.1)
..but:
$ sudo usbipd -d
usbipd: error: failed to open /usr/local/share/usb.ids
libusbip: debug: usbip_host_driver.c:244:[open_sysfs_host_driver] sysfs_open_driver_path failed
usbipd: error: please load usbip-core.ko and usbip-host.ko!
(should be smart enough to realise usb.ids is gzipped
and, from the tinycore .config:
# CONFIG_USBIP_CORE is not set