Here are several of your options:
ACE Secure Data Portal
CBP offers a web-based method for creating and filing e-Manifests. Once a fleet establishes a portal account, it types manifest data into a fill-in form using a standard web browser. While the price is appealing, this option will probably be used by very few since it involves manual data entry for each crossing. Instructions on setting up a carrier account are available by email at ACENow@dhs.gov or by calling 703-336-4326.
Internal EDI interface
Fleets with in-house EDI capabilities can develop their own e-Manifest interface for ACE or purchase existing record layouts from a provider. The cost and complexity of maintaining EDI will limit this option to fleets with the volume and resources to justify in-house EDI.
Certified Service Provider
Existing EDI third-party providers are obtaining certification to add e-Manifest services to their offerings. While the ACE portal provides basic functions for creating and submitting e-Manifests, third-party solutions offer a wider range of customization and integration options.