Not true...
You can use PPP Serial connecton to act just like the dial-up connection (with regards to the TiVo Functions).
The DVR software updates, come down via the SAT. But are activated by a dial-in to the servers. But for the R10 there are no updates, so nothing to worry about there.
The PPP Serial "can" be used to do the initial setup... but if that is what you are only going to use it for... I recommend that you drag the box over to a friends house and ask them if you could do it there (NOTE: They DON'T need to have a SAT setup for you to complete the setup).