Using Sections navigator

This approach applies to other help calling methods but is more applicable to the TiddlyWiki approach. 

You can create a Section (eg named "HELP" or whatever you want). In 'Edit Preferences', make sure that Sections are navigable. 

Now you have a sidebar on the right side of the page (in the standard skin, anyway) from where you can call your Help system at any time, without disturbing the flow of the case. 

Because Sections only allow you to link to a page, not to a file, you do have to put up with the cumbersome step of calling that Help page, and then from there, the TiddlyWiki help system.