Don't you have a dash bar? That's where mine's attached. Dash bar sits just above the steering column.

Not sure if yours is an early or a later car... Note that it's also possible to go through where the center speaker vent is (in the early cars) and there's direct access to the firewall there. There's a small (M6?) stud which holds the dash on, and could be used, or cut out, replaced with a larger attachment point.

Consider also that the center net does not need to be purely straight front-to-back; it is often best to have it laying against and wrapping around the seat back, and angled forward away from the driver (like over/past the shifter). This could allow you to go right past the RH side of the center console and attach to the firewall wherever you like, under the dash.

Again, mine's just on the dash bar.