With great difficulty.
It is possible, but sadly Solaris does not know about "netstat -anp" or "lsof".
Instead you have to use the "pfiles" command on every running process and keep looking until you strike gold. For example:
# for pid in `ls proc` > do > echo $pid > pfiles $pid | grep PORTNUMBER > done
As so often with Solaris, you will need "root" privileges for this to work.