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