I was trying to get an SSIS package imported into a named instance using the command line utility dtutil and couldn’t get it to work.

This command had been working just fine with a default instance.
dtutil /File userdbbackup.dtsx /DestServer hostname /Copy DTS;"MSDB\Maintenance Plansuser\dbbackup"

But when running the same command on a named instance, I got the following:
dtutil /File userdbbackup.dtsx /DestServer hostnameinstancename /Copy DTS;"MSDB\Maintenance Plans\userdbbackup"

Microsoft (R) SQL Server SSIS Package Utilities
Version 10.0.1600.22 for 32-bit
Copyright (C) Microsoft Corp 1984-2004. All rights reserved.

Could not create SSIS Service Storage object because of error 0x800706BA.
Error (0x800706BA) while checking for the existence of package “Maintenance Plansuserdbbackup” in the SSIS package store.
Could not create SSIS Service Storage object because of error 0x800706BA.
Description: The RPC server is unavailable.

The solution was changing the DTS flag to SQL in the /COPY parameter. I also had to change the folder location by removing MSDB.
dtutil /File userdbbackup.dtsx /DestServer hostname /Copy SQL;"\Maintenance Plans\userdbbackup"

This means the package is getting stored within MSDB in the SQL Server rather than the SSIS Package Store.

Note that the commands above do not specify username and password. The commands were run on the local host with a privileged user that had a trusted connection to the DB.

Here are some links on the topic of getting the SSIS Package Store to work with Named Instances:  Robert Davis explains and Tim Cullen covers similar ground.

If I understand the above links correctly, if I manipulate the XML files as they indicate, the dtutil /COPY DTS can be made to work with named instances.

By the way, this concise dtutil tutorial helped steer me in the right direction. It even mentioned dtexec and dtexecui, both new to me.