Well, I have yet to atempt to do this myself, but the instructions states that you Lower soft top & lift the leading edge of the windshield header weather-strip (WHWS) & insert the vacuum hose under the gasket. (Sounds easy....lol). If you do it first, please let me know how it goes and I will do the same. But like I said, I have other issues first. My Capri is smoking and is idiling above the normal 8 rpms.
Also, if you go under Links on this websit to Mid county mustang. Under the the Capri Maintence page. Scroll down to the star symbol and click on "View a collection of Facts, Tips & Useful Information all about the Mercury 'Aussie' Capri", you will see information about the Capri. It will show you Facts, tips and useful infomation about the vechile. I found it very, very handy.
If you would like, I can email you the information, just need your email address.