LyX ⇒ Econometrica Template

[Gnosos]

When I load the template for the journal Econometrica, I get the following error message:

The selected document class
Econometrica
requires external files that are not available.
The document class can still be used, but the
document cannot be compiled until the following
prerequisites are installed:
ectaart.cls
See section 3.1.2.2 (Class Availability) of the
User's Guide for more information.

With some more investigation, I learned "[url https://www.e-publications.org/ecta/support/]Previously used ectaart package is now obsolete.[/url]" So how does one get the Econometrica template to work these days?

[JBClaypool]

can you provide a Minimal Working Example?
might be able to figure it out with the command(s)/environment.