Apple - re-mount ejected SD card without reinserting
On Mountain Lion with built-in SD readers:
sudo kextunload -b com.apple.driver.AppleSDXC
sudo kextload -b com.apple.driver.AppleSDXC
Type this in terminal:
sudo kextunload /System/Library/Extensions/AppleStorageDrivers.kext/Contents/PlugIns/AppleUSBCardReader.kext; sudo kextload /System/Library/Extensions/AppleStorageDrivers.kext/Contents/PlugIns/AppleUSBCardReader.kext
This will unload and load the card reader kernel drivers, and it will appear in diskutil again.
Thanks to binarybob for the pointers.
I have built an AppleScript out of Coolkah's solution:
display dialog "Your Administrator Password:" default answer "" with hidden answer set PWD to text returned of the result do shell script "sudo kextunload /System/Library/Extensions/AppleStorageDrivers.kext/Contents/PlugIns/AppleUSBCardReader.kext; sudo kextload /System/Library/Extensions/AppleStorageDrivers.kext/Contents/PlugIns/AppleUSBCardReader.kext" user name "your name" password PWD with administrator privileges