Is anyone aware of a prototype document that can handle specific union employees as the only eligible group of employees and have a service formula for contributions?

I am in the process of updating for GUST and EGTRRA an old Principal Group prototype and have come to the conclusion that I will have to go off a prototype (Corbel's cannot handle) and use modified language in Corbel's volume submitter, along with application for IRS determination.

Any help would be appreciated. Client is a small paving contractor and not looking for anything fancy by any means.

Thanks.