Check the output of pci -vvv , and look for your nic card. It should give you some info on vendor id and bus id. Try passing those as parameters to your nic driver (to see those options do a “use /lib/dll/devn-sis9.so”). Parameters for options are comma (not whitespace) delimited.
If that still not work, you are probably out of luck. As far as I know, QNX’s sis driver only supports a subset of SIS900 NICs