The way I see it, there are bascially to good ways to handle this.
#1 - Saddle horse, load in trailer and drive out to pasture with another person. Unload horse, tell other person to stay back until you get the animal caught, and then bring trailer to you once you have it roped. Then ride to the herd, single the animal out and rope it. Hold it until the trailer gets there, then use horse power to drag animal into trailer. Take animal back home, and put in secure corral for a while until it gets used to your place before you turn out again.
#2 - You and another person go to pasture and call the herd up to the pens. When your animal has went into the pens, probably with many others, shut the gate. Then you go into the pen to sort, while the other person mans the gate. Let most of the cattle out, keeping yours in, until you have him and maybe a couple more in there. Back up to the loading chute (or wherever you can load from) and load your animal. Take animal back home, and put in secure corral for a while until it gets used to your place before you turn out again.