Hi Amy Bancke 
The Office Add Ins are installed through options when using the CM Client installer, or added to the cmd line install, see P19-21 of the 10.0 install guide.
There are alternative options to use the ThinOffice Integration,  see p54.

As 10.0 is no longer under maintenance, and10.1 ends later this year  Product Support Lifecycle | Micro Focus, it is worth considering an upgrade to one of the later versions which will also include fixes to known issues as well as any enhancements.  

Thank you,  . Yes, we are planning to upgrade. Will the integration functionality change substantially in 24.4? In other words, should we just wait until the upgrade or should we work on it now? 

Hi Amy Bancke 
Although each release may result in additional functionality, e.g. 23.4 introduced the ability to Enable native Content Manager User Interface instead of the built-in User Interface for Office integration,  I would not expect the capabilities to change substantially.

If you wanted to get onto a supported version asap you could download and install CM 23.4 in a separate development/test system enabling you to evaluate any changes before carrying out any actual upgrade. As 24.4, the 24.x version with longer term support, should be available around Oct you may want to wait for the very latest version to upgrade to instead. Note: 24.3 is available and would give you an idea of the key changes in 24.x. 


You should also read New Outlook and CM - Content Manager User Discussions - OpenText Content Manager (microfocus.com) in case this affects you