It depends solely on the font or fonts that you are using. Tibetan Machine Uni
seems to have everything I have seen in sadhanas. Since you are using Open Office, one way to select the glyph initially is to go to Insert -> Special Character and select it directly. This is a bit laborious though.
The writeup at digitaltibetan.org says to use Chris Fynn's Jomolhari as the primary Tibetan font but he does not include very many special symbols that one can see in sadhanas (he seems to be more oriented toward just the Tibetan itself). You might ask him what he uses for these other symbols (maybe he has another Jomolhari font for these symbols).