They have poor English skills. I have access to prior tests, and can buy any books or cd's etc that I want. I have been thinking of a sight learning approach i.e. breaking the test down to essential phrases, and individual words and introducing, perhaps 5 phrases per day and drilling, drilling, drilling. I'm not sure that this is the best approach. The test is of software design, not English proficiency Can anyone offer suggestions?

I believe your approach will work the best. Remember that mathematics is the universal language, and the chief responsibility will be to convey the meanings of the instructions. You shouldn't have to teach them the mathematics, only how to understand the instructions.

Good luck to you and your students.