It seems that currently Memsource Editor and Memsource Web Editor do not work with any of the Xbench Input Transfer settings to copy the marked text to the clipboard automatically.
Also since the Ctrl+Insert is captured by Memsource to copy source to target (Ctrl+Insert is a standard long time hot key for Copy to Clipboard in Windows), you cannot use either the trick to press Ctrl+Insert and then Ctrl+Alt+Insert. It looks like a lot of keys but it's instantaneous because you nearly do not move your fingers across the whole sequence.
So probably the best alternative (at least until Memsource does not allow to configure your key bindings) is to change this key binding in Xbench:
- In Xbench, choose Tools>Settings
- In Source Hotkey, choose Ctrl+Alt+C.
- Click OK.
After this change, you can use the 5-key sequence Ctrl+C, Ctrl+Alt+C, which is also nearly instantaneous to press (but perhaps not as convenient as Ctrl+Insert, Ctrl+Alt+Insert) to search instantly the marked text in Xbench.