Hi:
I'm not sure what you mean by a "stored procedure or model". In SAS Enterprise Guide, if you design a project, with a Query to extract data, you could use the Parameter Manager to prompt users for the year or the merchant or both.
SAS does not have "stored procedures" such as RDBMS systems have. However, SAS does have "stored processes" which work within the context of the SAS Platform for Business Analytics to allow multiple Platform clients (including EG) to run stored processes (which are SAS programs that are registered in the metadata and can also have parameters or prompts to control the program output.)
Many SAS Statistical procedures use a MODEL statement -- I am not sure what you mean by "model" in your question.
Perhaps if you could explain a bit more about how you are using EG and SAS (local EG and local SAS; local EG and SAS on a Server; EG as part of the BI Platform -- with the BI Server or Enterprise BI Server configuration) and where your data is coming from ("flat" file; regular SAS dataset; other external file; SAS dataset defined in the BI Platform Metadata; other SAS datasource (such as an Oracle table, Sybase table, etc), it would be possible for someone to get you pointed in the right direction.
cynthia