|Well, the first thing I would do is is set the VBAProject properties for your workbook to "Lock project for viewing" and assign a password to the VBAProject itself so that the hardcoded passwords can not be seen by the casual user.|
In the VBE, right click the VBAProject (Workbook Name) and choose VBAProject Properties. Then click the Protection tab and fill in the requested information.
If the Password for the VBAProject is not stored anyplace where the casual user can find it, they won't be able to see the hardcoded password in your actual macro.
That said, I have never tried to modify VBA code via VBA code, but a Google search led me here, which appears to be along the lines of what you are trying to do:
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.