Enhancement spot RSL_WORKSPACE for BW Workspaces provides you with two BAdIs:
RSL_WORKSPACE_BADI: Enhancements of BW Workspaces
RSL_WORKSPACE_DESIGNER_BADI: Enhancements in BW Workspace Designer
You can learn how these are used by taking a look at the example implementations.
For more general information about using Business Add-Ins (BAdIs), see Business Add-Ins (BAdIs)