I would like to help you on configuring pix for this purpose. Here is some configuration steps
Pix#config t
Pix(config)#ca generate rsa key 512
Pix(config)#ssh 0 0 outside
Pix(config)#aaa authentication ssh console LOCAL
Pix(config)#username cisco password cisco123
If you are using PDM you can go under tools and command line and enter the lines one by one. If you get an error saying that you already have key generated, just continue with the next line.
You can also go through the following documents for some information,
http://www.cisco.com/warp/public/110/pixfaq.shtml
http://www.cisco.com/warp/public/707/cmatrix.shtml