How to make IRISLIB/HSLIB writable on Docker?

I know this is not recommended but I need to investigate a bug and to modify some system classes.
When I set the "Mount as read-only" flag to "off" IRIS says:

ERROR #43: the write daemon failed to set the READ/WRITE flag in IRISLIB
This database is mounted as read-only due to 'Failed to access iris.lck file'!