Change default ssh:// behavior
If you don't mind using some command-line tomfoolery: 

osascript -e 'tell application "Terminal" to activate' -e 'tell application "System Events" to tell process "Terminal" to keystroke "t" using command down'


This is from a stack overflow question on a similar topic.

If you want you can even create a new URL handler (or replace the ssh:// one) with a shell script as described at another stack overflow question.

EDIT1: you can get command line args from osascript by using something like the following (taken from the osascript man page):

a.scpt:
on run argv
    return "hello, " &amp; item 1 of argv &amp; "."
end run


% osascript a.scpt world
hello, world.