Below shows you how to enable ASDM upon your PIX.

First of all you will need to copy the ASDM image to you PIX firewall. I find the easiest way to do this is to enable scopy (scp) on your pix using the command ssh scopy enable. And then using the putty tool pscp to copy the image across to your PIX,

C:\Documents and Settings\admin>pscp "C:\Document~\admin\Desktop\asdm613.bin" admin@2.1.2.1:asdm613.bin
admin@2.1.2.1's password:
asdm613.bin               | 4696 kB |  16.3 kB/s | ETA: 00:02:44 |  63%

Once your asdm image is copied across your will need to enable the image, the http server and what management IPs you require. In this case will will let the 10.1.1.0/24 connect from the inside interface.

pix# sh flash
Directory of flash:/

     4      -rw-  37280       06:56:52 Aug 15 2008  downgrade.cfg
     7      -rw-  7630848     10:48:16 Apr 21 2009  pix804-28.bin
     11     -rw-  7562988     19:08:00 Aug 11 2009  asdm613.bin

16180020 bytes total (845312 bytes free)

pix# config t
pix(config)# asdm image flash:/asdm613.bin
pix(config)# http server enable
pix(config)# http 10.1.1.0 255.255.255.0 inside
pix(config)# wr mem

And that's it. If you need to create a read-only account you can find the guide here.