I'm not sure I can get it as clean as the picture. I'm planning to spray it with brake clean and clean it with a brush from the two holes at the bottom
Found this in LS1tech forum
"Yeah, it's super simple/easy...just a bit of a PITA..
1. get a turkey baster that you'll never re-use for food( pretty obvious, I know), and use the baster to suck out the fluid in the reservoir.
2. there are 2 roll pins that need to be knocked out to get the reservoir off. I pounded mine out towards the engine, it gives you more room to get them back in. Use a long screwdriver on the roll pin in the back. hit it till its flush with the master, that should push it out of the other side enough to pull it out with pliers. the front roll pin is easy.
3. after the roll-pins are out, you'll need to lightly pry up the reservoir to unseat the o-rings. Make sure you put a few rags under the master and atop the fender to catch any brake fluid that may splash.
4. To install the new reservoir, I recommend 2 things:
1.after installing the new o-rings on the reservoir,wipe the new o-rings down with brake fluid before you seat the new reservoir.
2. Use a short nail, or short punch(something with a point, the point should fit inside the roll-pins), to re-install the roll pins from the engine side.
Refill the reservoir, then pump the brakes a few times, and re-check the fluid levels"