Have a look at the command design pattern described in
The Design Patterns Smalltalk Companion. Annotate the accessor methods that configure the command with Magritte; let the user edit the command object; then execute the command as described in the book.
Pier pretty much builds around this pattern for all user invokable behavior (see the PRCommand hierarchy).
Early versions of Pier used some kind of a naming convention to describe the arguments of methods. This was not very readable and led to problems with reusability and extensibility of commands.
Cheers,
Lukas