Duke nukem on goldsource, now that would be something.
The shrink ray, I think that's beyond GoldSource's capabilities. Freezethrower would work, as all it would have to do is freeze the animation and apply a frozen overlay, not unlike the shockroach in Opposing Force.
As would be the devastator, though I can't vouch for the stability of that, since its a full auto rocket launcher. Might could modify Half Life's native RPG for that one, sans the laser guide. Or perhaps use even the Hivehand for a base code, and have it shoot rockets instead of hornets. Again, excessive use will probably crash the engine.
Again, might have to do without the shrinkray, unless of course you can perhaps find a way to model tiny versions of each model, and find a way to seamlessly replace the npc model... considerably a lot of work.
By the way, do you already have models? I have stumbled across some DN3D models from some 3D project mod for DN3D way back; they're unrigged and need a lot of work but.... well, figure I might let you know. Of course you'll have to hunt down the creators if you want to use them, I'm sure --- probably a wild goose chase. I'll get you some pictures sometime, if you're serious about this project.