You cannot directly save the TestStand 3.0 sequences to 1.0. TestStand can save formats upto two versions previous to the current version. So TestStand 3.0 will the sequence into either 2.0.1 or 2.0 version.
However if you have TestStand 2.0 on your machine, then you can open this TestStand 2.0 sequence and save it as TestStand 1.0 sequence.