I would
1.Download the patch, it will be file of type RAR.
2.Make a Hauptwerk back up (File | Backup). This preserves your settings (including the voicing changes)and I would take it as a precaution.
3.Install the patch file in the sample way you install sample sets. (File | Install), when the dialogue box appears during the install, click OK to complete the patch installation.
4.Load the organ as usual, it will probably want to regenerate the cache file and so will take quite a bit longer than a usual load operation.
5.Try the upgraded instrument. Your voicing changes should still be in place. You may need to review them if the patch has changed some of the ranks you have voiced.
If for some reason the voicing is not preserved, you could restore the backup made at the start.
Hope this helps,
Iain