I have some python scrtipts that I use to work with my smalltalk images. I will post them as soon as I get home (probably tomorrow)
With this scripts you can do something like

$ smalltalk open pharo 1.3 with cog

which does what you expect

although its quite hardcoded to my system and my needs so I will have to modify them a little bit before sharing to make them of any use for someone else.

Cheers
--
Alan Rodas Bonjour