Does your horse already sidepass? If he does, you should be able to get him over the log with just a little time and effort. Maybe you could start out with a pole or branch on the ground, then gradually work up to bigger things until you're sidepassing over a log. I don't know how big 4-H logs are, but I've seen logs that can get pretty big for the horse. Like with Jester the log almost touches his stomach, but that was the extremely higher level trail and I only did it because I wanted to go for High Point.
Pssh.I didn't pick up the wrong lead
It's called a counter canter...
...A very advanced maneuver.