If there is interest, I could include the basic functionality into RB itself. I think that would be much cleaner and easier to use.
The latest RB (Refactoring-Core-lr.5.mcz) integrates the functionality to ignore certain SmallLint rules in particular methods. Contrary to the original RB implementation it uses pragmas that are persistent with the method. The original RB used a global dictionary that was not tracked by versioning systems.
If the rule 'Messages sent but not implemented' should be ignored for a particular method add the following pragma:
<lint: 'Messages sent but not implemented'>
Normally you also want to add some more information about your rationale:
<lint: 'Messages sent but not implemented' rationale: 'We are doing metaprogramming trickery here' author: 'Lukas Renggli'>
Contrary to my original implementation in the Essential package don't put a symbol to identify the rule (that doesn't work without changing a whole lot of RB), but just the title that also appears in the result browsers.
Furthermore I added several new rules to Lint: This is to detect not categorized methods, violations to the Law of Demeter and unconditional recursion. These rules were also formerly part of the Essential package and can now be used from the standard RB tools.
Cheers, Lukas