You can download the demo version http://www.maxon.net/downloads/demo-version.html
MAKE SURE THAT YOU ONLY INSTALL BODY PAINT IT WILL BE VERY CONFUSING IF YOU INSTALL CINEMA 4D except for when you start up the installed body paint and it asks you which version you want. then you can select the one you prefer.
To start texturing your model click the icon that has a paintbrush over 3D
this unwraps your model. on the bottom left of the window u will see a progress bar loading. do Not do anything no matter how small the program is your computer (if it is like mine) will lock up and take forever to get back up again.
Next click the icon next to it and don't bother changing any settings in the dialog box that this opens just click the next buttons until the program creates your base texture.
then texture to your hearts content
Hidden/Spoiler:
after it has been imported into XSI either use RepSharpshooter's MshEx to convert or use the PandemicXSIAddon in XSI Foundation.



