If you really want to control a stargate from tablet, it would require writing a networked program. I will not explain how to do that as that is out of scope of the question.
What you need in first place, is to place acomputer somewhere near the stargate you want to control, put an Adapter block directly next/under it or something, and connect to the computer.
Sadly, any exact tips on how to control the stargate are not possible as you have not provided the information of what mod you're using. Best bet is to look at the dscription of the mod and look for OpenComputers API description in
