Calling an application from IE menuext

[Cesarion]

Hi! Someone knows how can i set a register entry to configute IE menuext to call an application like notepad passing the selected word in a command line argument?
Clearing: I want to select a text word in the browser (IE) and, when right click over this word, appear a popup menu with my item. Ok, I know how can I do it: setting in the register something like
HKEY_CURRENT_USER
Software
Microsoft
Internet Explorer
MenuExt
My Menu Item =
But, how can I call an external app from ? How is the command sintax to call, for example, the notepad.exe?

TIA!
Cesario
From Florianopolis, SC, Brazil