A standard sized bander will work just fine on one that young. When Boogie refers to small bands, he means the ones that look like little rubber Cheerios.
The Basics: Slide the band onto the closed prongs of the bander. Get ahold of the calf and grab his cajones (easier for me if I have one person hold 'em while I band, but then again the calves far outweigh me by 2 months old). You'll more than likely need to pull both testicles down into the sack (just press up into his belly and push it down - you'll feel it). Make sure you've got both of them firmly in hand, hold the sack just above the nuts and stretch the sack down. Depress the handle on the bander to open the band and slide it over both testicles. Release the handle, putting pressure on one side of the sack with the band so you can slide the bander out. Count the testicles again before releasing to make sure one didn't slide back up on you.
Some people give a tetanus shot as routine, some don't. If you've got him down, you may as well give him the shot as a precaution. Either way, just keep an eye on him for any major changes in feed/water intake, weight, listlessness, etc.
Have fun!