Are you the owner of the server, does it run bukkit and do you know how to write Java? If all of the above are yes, I think it would be easiest to create a small plugin that achieves this. If you don't, the best is to look at the other answers.
It is very easy to create a command listener that dispatches more commands when it activates. You can then use a /tellraw to call this command. Here is some example code:
package my.pkg;
import org.bukkit.Bukkit;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.plugin.java.JavaPlugin;
public class MyPlugin extends JavaPlugin {
@Override
public boolean onCommand(CommandSender sender, Command command, String alias, String[] args) {
if (command.getName().equalsIgnoreCase("mycommand")) {
Bukkit.dispatchCommand(sender, "command1");
Bukkit.dispatchCommand(sender, "command2 with arguments");
Bukkit.dispatchCommand(sender, "command3");
}
}
}
What this code does is listen for /mycommand. If someone does this command (by clicking a link from a /tellraw message for example), the code will automatically fire the commands /command1, /command2 with arguments and /command3. These commands can be any command, like the /setblock you mentioned.
For more information on creating plugins, here is a (slightly older, but still viable) video:
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