Luckily for you KnownHost are semi-managed and good guys so they'll do pretty much everything you want them to do I'm sure if you ask nicely ;-)
We consider ourselves a semi-managed VPS company. We will apply Operating system and applications updates for standard applications such as PHP, MySQL, Apache, etc based upon your request. As well, we will help with 3rd party products you want to install aside from the applications we install upon delivery of your VPS. To request 3rd party application installation simple open a support ticket and provide detailed installation instructions.
Just read up on various SSH commands (it's easy with cPanel/WHM) but do not
try any command that you are not sure of - it could have nasty results :-)
If you really get stuck you could always get a company such as PSM to manage it for you.
And finally - good luck with your new VPS.