Hello Chris,
With the CODM you can have reiterating percussive ranks, please see the CODM user guide at http://www.hauptwerk.com/documentation.
You can adjust tuning, brightness etc. using the voicing controls with the Advanced Edition of Hauptwerk, or you can use the parameters within the CODM format using features such as
<HarmonicShaping_PipeMIDINoteNum036_3rdAndUpperHarmLvlAdjDb>0</HarmonicShaping_PipeMIDINoteNum036_3rdAndUpperHarmLvlAdjDb>
<HarmonicShaping_PipeMIDINoteNum096_3rdAndUpperHarmLvlAdjDb>0</HarmonicShaping_PipeMIDINoteNum096_3rdAndUpperHarmLvlAdjDb>
These are all documented within the CODM user guide, so be sure to read through that and it should answer most of your questions.
I hope that helps.