The main sad thing in migrating older xenapp versions to xenapp 6.5 is, mixed farms are not supported in xenapp 6.0, 6.5 and there is no direct upgrade from older versions to 6.5. If you have presentation server 4.5 and you want to migrate to xenapp 6.5, we first need to upgrade to xenapp 5, and then to xenapp 6 and then to 6.5. There is no direct upgrade/migrate to xenapp 6.5

Tools to migrate to xenapp 6.5:

We already have migration tool(both GUI and powershell Cmdlets) in xenapp 6.5 setup. In order to migrate xenapp 6.0 to xenapp 6.5 we just have to execute only two commands.

1. set-executionpolicy remotesigned

2. start-xamigration -remoteservername

Lets see how to execute this commands with powershell:

Goto the path start-> administrative tools-> citrix-> xenapp migration -> Windows PowerShell with Citrix XenApp Migration Module. Execute the command:

set-executionpolicy remotesigned.   Press Y when prompted.

Now it is time to execute the second command.

start-xamigration -remoteservername

ex: if your xenapp 6 server name is XA6 then execute the command as start-xamigration -remoteservername XA6.

Using GUI tool:

Inorder to use the GUI tool, we still need to execute the first command set-executionpolicy remotesigned, in the same powershell console mentioned in the first step. Then goto the path start-> administrative tools-> citrix-> xenapp migration -> Citrix Xenapp Migration Center. When you start this, it would take some time to initialize the enviornment. When prompted for source server name, enter your xenapp 6 server name. Next analyze your settings and click Migrate to target farm option.  All your settings, administrators, worker groups, applications, policies etc would be migrated to xenapp 6.5 server.

Now open citrix AppCenter and run, Configure and run discovery and you can see all your xenapp6 settings in xenapp 6.5

You can find some more info on migration here.