Vector Graphics in Altium
Altium currently lacks well-integrated support for putting vector graphics onto the silkscreen. There are a couple of workarounds for this. SSI's preferred option for vector graphics that will be re-used is to add them to the SSI font.
Using an existing logo
The SSI Altium libraries SVN includes an "SSI Logos" font that already contains most of the logos you might need (including SSI logos, team logos, and sponsor logos). You can find the font here:
Install the font by double-clicking and pressing Add or Install.
Then launch Altium and insert a String on the Top or Bottom Overlay layer. Select TrueType font and choose "SSI Logos" as the font.
Each logo corresponds to a particular character. For example, typing 'A' will insert the SSI Logo. You can find a full list of available graphics here: