Setup the CDU in the usual Boeing way, with your route and the SID's and STAR's at both ends, and then enter your performance parameters (it may be OK without the STAR, but this is how I have managed VNAV using the CDU at this time).

Configure the MCP correctly with RW heading and V2 + 20kts, plus the first altitude constraint in the windows.

Start your take-off roll, rotate as normal, and engage the AP during your climb out with LNAV and VNAV - the trick with the VNAV is to click the VNAV button but keep holding the mouse button down, then slide the cursor off the VNAV button, and only then let go of the mouse button.

Right, VNAV should be ON, and the CS777 should be on AP with LNAV & VNAV. VNAV may disconnect when you reach a constraint, so just re-engage it as above.

I had trouble with the rest of the climb, as the aircraft climbed far too slowly (500 ft/min), and the TOC was just a few waypoints before my descent. What I then tried was to cut the corner off the STAR (DCT next waypoint), and then enter your next step altitude or cruise level into the MCP.

I've tried this a few times with good success.

I'm asking others to see if this or something similar works, and for us to gradually get an idea of how to enable VNAV.

I believe VNAV works, but we have the figure out the tweaks to get it to work reliably for us.

Also, I use AS2012, and I had too much wing rocking, so I implemented the [custom autopilot] aircraft.cfg tweak with excellent results; change these values, but make backups first:
Custom Autopilot]
AP_Roll_speed=4
AP_Roll_window=7
AP_Roll_controlstep=1500

Finally, the aircraft hasn't changed its thrust rating from TO to CLB, but this can be done within the CDU thrust page by clicking on the LSK next to [arm] cruise. The CS777 will, however, change from CLB to CRZ. This does not stop the engines red lining, so look away, and remember that you won't be paying the maintenance bill.

Good luck, but please add your comments and ideas to this post.