Hi Kilon,
a simple way to do that is to change your configuration so that it uses the baseline in your github. The SmaCC configuration for Pharo 4.0 is written in this way for the stable version.
version204: spec
��� <version: '2.0.4' imports: #('2.0-baseline')>
��� spec
��� ��� for: #'pharo4.x'
��� ��� do: [
��� ��� ��� spec
��� ��� ��� ��� blessing: #stable;
��� ��� ��� ��� author: 'ThierryGoubier';
��� ��� ��� ��� description: 'SmaCC Smalltalk Compiler Compiler for Pharo 4.0'.
��� ��� ��� spec
��� ��� ��� ��� baseline: 'SmaCC' with: [ spec repository: 'github://ThierryGoubier/SmaCC:master' ];
��� ��� ��� ��� import: 'SmaCC' ]