Yes you can. The easies way would be to have some steps already in you sequencefile, so that you can clone the step.
The Programmer Reference Help will also provide valuable information as well.
I think the example in the TestStand folder examples\SequenceFileBuilder uses this technique. Also I have provided a link to an example on NI website that maybe of help.
You will have to remember that if you are doing this on a target system, that system will require a full development licence. The deployment licences donot allow creations of sequencefile (which is what you will be doing) only the execution.