Editing contents of a WSP (SharePoint)

1. Rename the WSP to CAB
2. Extract all contents to a folder – using Windows Explorer, or WinZip, WinRAR, or whatever
3. Change the items you want, ie. MANIFEST.XML and remove a DLL (in my case)
4. Create a new CAB file with the updated contents, using IZARC 
5. Rename the newly created CAB to WSP
6. Install to SharePoint 

PS: using IZARC

1. Open IZArc as a ‘program’
2. Create a new archive
3. Choose a CAB file type
4. Add the files – and check the box for “subfolders”