opkg will install the packages from the sd card if you give the full path/file name, something like:
opkg install /mnt/sda1/kmod-hid_3.3.8-1_ar71xx.ipk
You need to satisfy the dependencies yourself, for instance you would need to download and install these first:
opkg install /mnt/sda1/kmod-input-core_3.3.8-1_ar71xx.ipk
opkg install /mnt/sda1/kmod-input-evdev_3.3.8-1_ar71xx.ipk