The blueprint is already established: In 1992, Congress amended the Cable Act to protect independent cable networks against discrimination by vertically integrated cable operators.
This explains why, for example, the NFL Network brought a discrimination cases against Comcast a vertically integrated cable operator that owns a national sports network under the Cable Act and not under the Sherman Act.
Once an agency is designated with the authority to police Google and other vertically integrated search engines (Bing included), website rivals could pursue individual discrimination claims just like the NFL. Importantly, website rivals would have to fund these battles, not with taxpayer money (of which millions were likely spent by the FTC in its antitrust investigation of Google), but with their own resources.