Is it possible to set default value for bill set parameter at generate invoice program?

Summary:

We would like to set a default value for Bill Set parameter at Generate Invoice Program. Job Schedule is NOT an option for us.

Content (required):

In our scenario we have a contract with two different lines and two different bill sets and we are generating two different invoices. To do this when user is running Invoice Generation program user has to select the correct bill set.

Our idea is to create a job set with invoice generation program and set bill set parameter with default values. So user doesn´t need to select each time. We don´t want to schedule, user wants to run when is necessary.