Warriors lost out 14-7 in Galway last Saturday after going down to 14 men when prop Sila Puafisi was sent off.
That defeat denied Warriors a home semi-final.
Gregor told BBC Scotland: "We know we have to be controlled even when we are under duress.
"There were times in that game where we let the noise or things that had gone against us affect our decision-making.
"We started the game well and at the end managed to get close to the Connacht line as we tried to get the draw that would have earned us a home semi-final.
"It's just the bits in the middle that we need to work on - our decision-making, our execution and also our emotional control which led to us giving away a couple of soft penalties.
"We know a little more about Connacht having played them on Saturday, and about whether our blend will have to change.
"But there's something to be said for that group of players to get that second chance because they have that immediate experience of playing against Connacht.
"They were very tough, aggressive, tackled well and tried to move the ball early. They did a couple of things in attack and defence we hadn't seen before.
"We saw enough to know they are a tough team who play with pride and passion and on a dry day we know they are going to move the ball about."
No team has won an away semi-final in the history of the Pro12, but Townsend says his players are capable of breaking the trend.
"It would be nice to break the record, we'll have to do our very best to do that," he added. "We have experience of winning semi-finals.
"Connacht play with a lot of passion at home, the atmosphere there is like Scotstoun, really noisy and tough for referees.
"I hope the referee is strong and not influenced by the crowd. As a group we need to stay strong too.
"If decisions go against us we must keep focussed, but I have huge belief in the players and that we can come back with a win."