How can I mount an EXT4 USB drive on Windows 8?
you will have to use 3rd party tools to access EXT4 file system on windows 8.Some options include :
- Ext2Fsd
- DiskInternals Linux Reader
- Ext2explore
you may find more info here - http://www.howtogeek.com/112888/3-ways-to-access-your-linux-partitions-from-windows/
HTH
You can try out Ext2Read, it seemingly works with 8.