replacing trans range sensor

After doing some searching on this forum and other sources it appears the transmission range sensor for my 1996 sable is faulty(no radio,power steering etc. when in reverse). By looking at the part, it seems fairly straight forward to replace(three bolts total). However, I keep seeing references to an alignment tool. I priced them, only about fifty bucks. Some other users indicated they changed it and didn't mention anything about an alignment tool. Is this tool really necessary? If so, how the heck do you use it? Thanks.

I haven't looked at my '96 Taurus yet, but I have an '87 Taurus wagon that I changed this switch on. This is the switch on top of the trans, right?

I used a small drill bit for an alignment tool. The Chilton's manual described how to do it; it wasn't a problem.