best way to flush PS fluid

[Princess Valiant]

I was looking at the power steering fluid in my friend's duster and it looks like Baby diarrhea......so my question is:

what is the best way to change all the fluid out .....I want to assure it all gets changed, even in the depths of the gear box.

 

[halifaxhops]

I would think take the low pressure side hose off and drain it and also blow out the box from the high side. Fill it up run it and drain again? No idea if an engine type flush will work because I have always used tranny fluid for engine flush.