Tricky, then. If the program is classed as an "aplication" then the taskbar will show it. I've seen various commercial (but not entirely mainstream) tools that suffer from this sort of taskbar pollution.
More geek answer: Many commercial applications, such as the MS Office products, also have a COM API to access some of their features. It may be possible to write a short program that itself doesn't show up in the taskbar and uses the function you want in this way. Requires expert knowledge and tools.
Re:
More geek answer: Many commercial applications, such as the MS Office products, also have a COM API to access some of their features. It may be possible to write a short program that itself doesn't show up in the taskbar and uses the function you want in this way. Requires expert knowledge and tools.