Remote RESTORE of database through SSMS
What TCP Port is SQL Server running under? by Colin Stasiuk details several ways to determine the port number SQL is running on


go right to the registry and look at the TCP settings

SQL 2005

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\
  MSSQL.&lt;InstanceNumber&gt;\MSSQLServer\SuperSocketNetLib\TCP\


SQL 2008

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\
  MSSQL10.&lt;InstanceName&gt;\MSSQLServer\SuperSocketNetLib\TCP\

xp_readerrorlog.  This will show the current SQL Server log and you
can find the row "Server is listening on".  
use the SQL Server Configuration Manager 
if you are on the machine, look at Task Manager


Then you should be able to use 'IPAddress, Port' to connect.  Or you can create a client side Alias using CliConfg on the client that allows you to connect to an alias.