You can change default Port for AS in msmdsrv.ini file of the Instance.
Port Used by SQL Server Browser Services for SSAS is 2382
How to determine on which port AS is running?
-Open Task Manager Get the PID for msmdsrv.exe
-Open command Prompt type netstat /ao >>c:\output.txt
-Look for the PID in output file and corresponding TCP IP:Port information for same PID
-To confirm whether you got right Port number, Open Management Studio and connect to AS using IP Address:Port Number (192.168.1.1:5585)
How to change Port for AS Services (2005 & 2008)?
-In Clustered environment, AS can listen only on Port Number 2383.
For standalone Default or Named Instance you can change port number in msmdsrv.ini file (<Port>0</Port>)
SQL Server Bowser is enumerating all SSAS instances and will provide connection information for them.
Imp: Not any default instance information is handled by the SQL Server Browser which means, if you’re using a default instance with an alternate port, you will need to provide it to the client application; SQL Browser will not be able to forward it at connection time.
SQL Server Browser will only provide the connection information for visible SSAS named instance.
How AS Port is Determined in Standalone or Clustered Environment?
What if I have multiple nic card on a box, how exactly SSAS will Listen?
-SSAS as a Standalone Instance
SSAS will start listening on all IP addresses of the box using the port specified in the msmdsrv.ini file or the default port (2383) if “0” specified.
SSAS will start listening on all IP addresses of the box using the port specified in the msmdsrv.ini file or an available port provided by the system if “0” specified.
-SSAS as a Clustered Instance (Default Instance or Clustered Instance)
SSAS will start listening on all IP addresses of the cluster group using the default port (2383). Any alternate port configuration is ignored.
Imp: In clustered environment AS can listen only on Port Number 2383, manual setting in msmdsrv.ini file will be ignored.
On same box you can’t run standalone and clustered instance:
How to: Configure Windows Firewall for Analysis Services Access
Managing Multiple Instances of Analysis Services
SE, Microsoft Analysis Services