You chose a not so linux-friendly printer, btw ... this may help
for the printers basic set-up (driver as such).
If that works for you:
Does Slack pick the Wireless device up as such?
If it does, and you're using CUPS as your print-system, it
maybe as easy as to
lpadmin -p <printername> -m <drivername> -v socket://192.168.1.122:9100
or, if the Linksys doesn't support this mode, maybe
lpadmin -p <printername> -m <drivername> -v lpd://192.168.1.122