Where can I find information on Dynamic Reconfiguration for 
Sun Enterprise 3X00/4X00/5X00/6X00 servers?

You can go to website http://sunsolve5.sun.com/sunsolve/Enterprise-dr/

Here you can get information on DR commands for specific OS releases.

You will be able to get updated information on

+ Required additions to the /etc/system file
+ Known DR Limitations & warnings by release
+ Supported boards & devices
+ Differences from prior releases 
+ Alternate Pathing issues
+ FAQ for DR                     

Additional documentaion on Dynamic Reconfiguration can also be obtain from http://docs.sun.com