Hi Bruce,
I just went through the process of getting a PHRF rating for my E-25+, and it was a fairly simple process. The standard rig dimensions for your boat should be readily available on the web from a variety of sites. What may change your rating (from the standard for the boat) are the dimensions of your sails and any modifications to the boat from its original factory layout. The hard part is really just laying out your sails and taking the required measurements according to the directions on the form (plus a few other measurements, spinnaker pole length, etc). It probably took me a couple of hours to leisurely get my sails laid out and take all the measurements, but if you're in a hurry, you could probably get it done much quicker than that. It helps to be in contact with a handicapper from a local yacht club in case any questions arise, so you may want to consider joining a club (if not already a member of one). Then make at least two copies of the completed form, and send one to the PHRF-NW (with the required payment) and the other to your club's handicapper (if you have one)...and then wait. I'm still in the waiting phase. My handicapper came up with my boats rating quickly, but he can't officially issue a certificate until everything clears with the PHRF-NW.
What you'll need: a large flat area; a 50' or 100' tape measure; and three stakes with bungee cords (to apply tension to the sails). A helper is not necessary, but would make the job much faster and easier.
Also, if your are only planning to do that one race, another possible option is to contact the handicapper or race director from the sponsoring club to find out whether they'd be willing to issue you a one-time temporary PHRF rating just for that race. I've heard of that being done, but you may still need to measure your sails.
-- Scott