Putting Hebrew text into Keynote has been done using images. In anticipation of what prayers the students would use, the major shaharit prayers were scanned. The images of those prayers were placed on the school server where the kids could all access them. These images can then be cropped to the part of the prayer they are illustrating. This has proven to be an efficient way of inserting Hebrew.
However, using Keynote, it is possible to write Hebrew directly into the text box, or copy and paste it from Mellel.
The scanned prayers look like the siddur and the students don't have to spend time choosing fonts and type face size.