You can download the manuals for free even if you're not a registered user IIRC - those provide basic explanations.
The statement you quoted refers only to complex sounds and there's no computer involved: it will behave that way even in standalone, directly connected to an amp, as mostly every other DSP based synth with dynamic voice count will. Simple sounds (there's also a meter on the display to help you) will probably have no noticeable problems even using 10 parts at once.
To do what you requested you would:
- Load the Virus Control AU plug-in
- Create 5 or more MIDI tracks pointed towards the Virus Control's MIDI port, with progressive channel number; each track will control the same numbered part
- Create at least an audio track to monitor and record the sound from Virus Control's virtual (usb) audio outputs
- Go back to the VC Gui to do the actual synth programming and part assigning, while/before/after writing your MIDI notes and events in the corresponding MIDI tracks.
There's a tutorial song for most DAWs that comes with the Virus software suite and some documentation on how to set up your system correctly. You can find other answers on the official forum at
www.virus.info/forum/ where there is a section for non-owners and where people who actually use Logic can explain better than me