I just went through this, and for 200 bucks in hose and misc fittings, plus 100 for the new/additional valve, I left the FEL thingie as it was and now have a third function for about $300.00. Here's the thread, it may help, it may also confuse you at first, it did me.
http://www.orangetractortalks.com/forums/showthread.php?t=34146
In the interest of full disclosure, I should mention my project is complete, but yet untested, as I wait for a "power beyond plug" that should have came with my new valve but didn't. This Tuesday or so it should arrive, and 5 minutes later I'll fire it up and see if it works. Bottom line is, I did like teg so handily summed up. The project started off simple, then got complicated, until I got educated, then got simple again. Understanding the terminology was a big part!