One, it is a forum policy that you must show us your attempt to answer a question before we can help you. Two, your question is very broad, making it difficult or impossible to answer without knowing more about the starting materials and the target. In at least one instance that I know of the same reaction can be tweaked to give almost exclusively trans or predominantly cis isomers, but whether or not this reaction is useful depends on the starting material. Now that I have reread your question, it occurs to me that you might be asking a different question versus what I originally thought. It sounds as if you have a cis-alkene and that you do not want it to isomerize in a subsequent reaction, is that correct?