There's no way to force the display of a particular command entry at the top of the ContextMenu.
What hpguru already posted
(include an ampersand in the command name)
is probably your best bet.
BTW, I've taken a different approach.
I have LOTS of "extras"; most of them are bookmarklets.
Cumulatively, they would clutter the ContextMenu so, instead,
I created a "Prx" folder under IE's "Links" folder...
...and HERE you can drag and rearrange the entries so that they appear in the order you want.
Move the "Prx" folder to the top of the "Links" menu, then you can have it appear (a "Prx" folder icon) appear on your toolbar. All your entries will be in the order you chose, and you might even want to create further subfolders, with those calling Prox commands & reloading the page into an new browser window placed together in one subfolder (flyout menu) and those that reload the page in same brwoser window with prox commands (dbug, etc) applied... place in a separate subfolder.