Which filetypes are you trying to add the option for? As a rule, all you
should have to do is go to the Registry, find the filetype and follow any
trail to locate the actual settings (Example: HKEY_Classes_Root\.exe
filetype is an exefile, so I proceed to HKEY\exefile, where the Open, Edit
commands, etc., are listed.) As a rule, you open the "shell" subkey, then
add a sub-key to that "shell" key named "runas", then a sub-key to that
named "command". Then look at the Open\Command key and copy the value(s)
from that key to the new Runas/Command key.
That works for most, but not all extensions. Use Find to locate keys named
"runas" to see more example.
This is the exefile section, for example:
-----------------------------------------------------------------------------
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\exefile]
@="Application"
"EditFlags"=hex:38,07,00,00
"FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,\
00,6f,00,6f,00,74,00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,\
32,00,5c,00,73,00,68,00,65,00,6c,00,6c,00,33,00,32,00,2e,00,64,00,6c,00,6c,\
00,2c,00,2d,00,31,00,30,00,31,00,35,00,36,00,00,00
[HKEY_CLASSES_ROOT\exefile\DefaultIcon]
@="%1"
[HKEY_CLASSES_ROOT\exefile\shell]
[HKEY_CLASSES_ROOT\exefile\shell\open]
"EditFlags"=hex:00,00,00,00
[HKEY_CLASSES_ROOT\exefile\shell\open\command]
@="\"%1\" %*"
"IsolatedCommand"="\"%1\" %*"
[HKEY_CLASSES_ROOT\exefile\shell\runas]
[HKEY_CLASSES_ROOT\exefile\shell\runas\command]
@="\"%1\" %*"
"IsolatedCommand"="\"%1\" %*"