First-half goals from Jimmy Smith and David Mooney kept the promotion dream alive although the Orient boss acknowledges that they are relying on other sides coming up short.
"We still have a chance of the play-offs. We are four points away from it, we have four games to go and other teams have got games in hand," Slade said.
"But they've got to win them and it could make it very difficult for us to get in but if other teams can't muster up those points, we're happy to take their place.
"We had to dig in, conditions were not great, the pitch was horrendous, there was a swirling wind and it wasn't easy. You have to give Bury because I thought at times they played some really sensible football on the surface.
"They got off to a better start than us and could have been two goals up before we went ahead but it is all about putting the ball in the back of the net and when we got our opportunities, we scored.
"They were two scrambled goals but I like to see those in the six-yard box with people going in but there were other chances for us to improve that score.
"We had two central defenders taken off with injuries but we still kept a clean sheet and that's got to be pleasing."