As you're probably aware, the IBM WebSphere MQ product has an administration GUI called MQ Explorer. This is included with the Server installation of the product on Windows and Linux (x86 & x86_64) platforms, and is also available separately via in SupportPac MS0T. What you may not be aware of is that you can also install MQ Explorer into other Eclipse-based products.
Firstly, it's best to use the "latest and greatest" version of MQ Explorer, which is V184.108.40.206 at the time of writing. You can still connect to remote queue managers that are at earlier levels, and benefit from the latest supported environments and new features of MQ Explorer, such as the integrated support for File Transfer and Advanced Message Security added in V7.5. (if you do need to access local queue managers with MQ Explorer, you should use the matching version from the same Server installation).
Next visit the System Requirements for WebSphere MQ page to find out the latest list of supported environments. Select the appropriate version and then platform, and then search for "MQ Explorer", as it's quite a lengthly document! There you'll find the supported environments, for example for MQ V7.5 on Windows at the time of writing it says:
MQ Explorer is supported when added to the following compatible Eclipse-based products:
IBM Rational Application Developer for WebSphere Software V8.0.3 or later fix pack, and V8.5 or later fix pack. 32-bit install only.
IBM Rational Developer for System z V8.5 or later fix pack. 32-bit install only. Requires WebSphere MQ APAR IC88187
Note that the second one needs APAR IC88187 because it runs with Java™ 7 instead of Java 6, but the good news is that the APAR is already included in the V220.127.116.11 version of MQ Explorer.
In order to add MQ Explorer to one of these environments, first install MQ Explorer as normal (from the Server installation or SupportPac MS0T), then selet Help > Install New Software... from your Eclipse-based product. Next locate a file called MQExplorerSDK.zip in your MQ Explorer install directory (for example "C:\Program Files (x86)\IBM\WebSphere MQ Explorer" or "C:\Program Files (x86)\IBM\WebSphere MQ\MQExplorer\eclipse") and either drag that into the "Install New Software" window or use the Add > Archive... buttons to select it. It's then just a matter of selecting the feature and following the instructions. Once you've restarted your Eclipse-based product you should be able to open the MQ Explorer perspective.
The other thing to note is that the 32-bit version of those products is required on Windows. That is because the queue manager is 32-bit on Windows, so you wouldn't be able to access local queue managers directly from a 64-bit version. If you don't need local queue managers you might be okay with the 64-bit versions, but strictly speaking that hasn't been tested so wouldn't be fully supported.
Accessing local queue managers is often straightforward, in fact it should be automatic on Windows if you only have a single default installation of MQ. If you have multiple installation and/or are on Linux, see the instructions in the information center.
The second product in the list, IBM Rational Developer for System z, has only been added recently, and is particularly interesting as it includes the CICS Explorer, so you can now run MQ Explorer and CICS Explorer in the same environment in a fully supported way.
Let us know in the comments below if there are other environments you'd like to see MQ Explorer supported with. Whilst you wouldn't be supported yet, you could even try them out and let us know if it appears to work. Environments based on Eclipse 3.6.2 or later have a good chance of working, as long as they include the "GEF runtime" tools from Eclipse. If you trying the latest Eclipse 4.2.2 release, you'll need to use the latest 18.104.22.168 version of MQ Explorer.