Co-op Portal - Part Two (Help Wanted)

I've come up with a complete design for a Co-op Portal level (see part one for some of the initial thinking around this). Now I need help.

If you're a Half-Life 2 mapper, I'd like to hear from you. Co-op Portal will be a single map consisting of 7 rooms. It will be be built on the existing Half-Life 2 Death match engine using only existing design elements from Portal (plus rocket launchers, which I've found a better use for). I'm quite happy to work on the scripting side, but I have no experience with Hammer.

It's important that you realise that Co-op Portal does not and will not be using the Portal gun.

If I don't hear from anyone, I'll start working on this myself, but obviously it'll take a lot longer.

Also I'd like to spruce up the design document before presenting it, by including the various visual elements. Does anyone have a good recommendation for design software (preferrably freeware) that could be used to get the same visual look as the Portal in-game artwork? I'd prefer to use isometric projection if possible. And does someone have the Weighted Companion Cube in a Visio template form?

[Edit: Looks like you can't put up help wanted on the Valve Developer Community without a mod, and they recommend you don't create your mod page until you have screen shots. Hmm... a little Catch-22. Besides which Portal is probably a registered trademark. Let's call the mod Lab Rats from now on].