Splitting a Networks on an older Allied Telesis x908 for Web Filtering

Good Afternoon Everyone,

I am reaching out to you all today in need of assistance with our Allied Telesis x908 (outdated, i know). We are looking to split the traffic to route internet traffic through to our Web Filter Appliance, and all other traffic to its local destination. We tried implementing a route-map using both access lists and preflix lists with no dice. We have three private networks (10, 172, 198) that we are looking to filter.

I can expand on what we tried, or answer any questions, but any assistance would be greatly appreciated!