It's possible, it just takes ages if u want it perfect, if you guys are interested im gonna be taking some pictures of it later, if u want I can post before and afters along with all the burs i used. For the record no one should try this unless you happen to have an extra m90 or plenty of cash to buy a new one, i managed to get one from a 2000 GTP for $60 at a pick-a-part.

 

I completely agree with that statement. You screw it up and you'll be without a car LONGER then planned sourcing a new intake.

It's not an M90, but I port matched a donor L36 lower intake with a Dremel. I used a lot of different bits, some trial-n-error. But the intake came out great and is on my Monte now.
Here's a link I wrote up on that process:
2004 Chevy Monte Carlo SS

Hmmm, in reviewing it, perhaps I should add some of the Dremel bits I used....
I found a great source for Dremel bits from Widget Supply.

Anycase, sorry to thread jack. Overdose, this is a great show-n-tell project!! Will be waiting for updates!

 

I ported the old polished M90 on my monte with a dremel. IMO, its much easier/quicker/cleaner to have the outlet done on a milling machine, especially to knock that H bar out, and to make sure you don't gouge anything (ie take a chunk out of the rotor sealing area, or damage the V or anything. The inlet is great for dremel/die grinder porting though.

 

Alright heres the pictures, sorry for the low resolution/quality, id otn have a camera so i used my phone. As Far as the bits/burs go theres plenty of variations to the ones i used that will work just fine. Just make sure you use a tungsten carbide one for the majority of the grinding, like this
9910 Tungsten Carbide Cutter / Model: 9910

Make sure you use plenty of WD-40 or something similar while your doing the grunt work. Not only does it allow the bit/bur/whatever you wanna call it to cut faster and smoother, it also takes alot of the stress off of your dremel, and those things get pretty damn hot when they're under stess. Plus it makes the metal dust and shavings clump up making it easier to clean everything. If you take your time with it most of it will be fairly smooth and wont require much smoothing, but remember, take your time, and mark out what your removing, if it take you 4 hours to enlarge the outlet by a 1/16 in. just remember thats better than taking 5 minutes to cut out 1/4 too much. Once you've got the majority of the work done you can move in with a good grinding stone like this.

8193 Aluminum Oxide Grinding Stone / Model: 8193

Again, go slowly, if you mess up the only way to fix it is the grind off more. Once you think its perfect, stop, come back in an hour and look it over, I guarantee you'll find flaws. Keep doing that until your absolutely certain you couldnt make it any better, no point going through the trouble of installing it if your gonna take it right back off to port more.\

Hmmm, maybe you guys should go into a bit more detail on your port/polish and we can get a thread full of write ups on how to port anything and everything on a 3800.