Decks, Patios, Porches and Docks - Help with Trex Deck Railing

First, let me admit that I'm in totally over my head and I know I've screwed up. That being said, if anybody can throw me a bouy, I'd appreciate it. I'm building a deck with Trex material. We've had issues from the start and are now trying to figure out how to put up the special Deluxe Trex Railing kit. Long story headlined, I have to install the railing posts on the outside of the deck. Bad or good, there is no other choice. The banister is pre-cut into 6-foot sections. No matter how I try it, there will be a 4x4 post perpendicular to at least one joist. Is this possible? Can I put a lag screw (instead of a carriage bolt) into the butt end of a joist without compromising the joist? Is there any magical solution to this problem? I'm at a complete loss as to what to do. Please help. I have a one-year old coming to visit in 10-days, and really want a railing on my deck before he gets here.

Could you cut a square hole in the deck flooring and pass the post down to an inside corner of two joists? The railing needs to be positioned over the floor, not on the outside of it.

You mentioned six foot sections. Does this dimension not fit your space? If not, could you cut the section to the correct length?

A photo would help here. Post back so we can figure this out.

Trex instructions are at the address below:
http://www.trex.com/products/railing/artisan/install_baluster.asp