Just add it to your cgminer.conf, like this:
"pools" : [
{
"url" : "stratum+tcp://middlecoin.com:3333",
"user" : "1E5PLsiUEzGqfLoLx5d1xpHF79jETTZcws",
"pass" : "x"
},
{
"url" : "stratum+tcp://eu.middlecoin.com:3333",
"user" : "1E5PLsiUEzGqfLoLx5d1xpHF79jETTZcws",
"pass" : "y"
}
]
You can add as many as you want.
You can also do stuff like auto-balance (mines all pools simultaneously), or failover-only, which starts at the top of your list and works its way down as servers fail. Google for cgminer.conf options and you'll get more details if you need it.