While Daspydyr's suggestion will work, the one drawback I see is that unless you have a metric crap ton of front brake cable slack you will either have to remove your handlebars or brake cable/brakes to allow you enough cable slack to pull the lowers off of the stanchions of the fork every time you want to "lock" your fork. I know you said you didn't mind there being some effort involved, but that just seems like a pain in the butt to me.
May I ask why you're specifically looking at the XCT? The reason I ask is that if you're willing to spend a bit more cash, you can get a better fork for what you want to do that has lockout. I paid $120 for my SR Suntour XCR-MG (not sure that particular model is made anymore, but I'm sure you can find a better lockout fork for that much or a tad less) and it handled all my commuting extremely well. The only time I've bottomed it out was when I hit a pretty big rock on a fast downhill on a mtb trail out here, and I'm not exactly a lightweight.
Another thing to consider is that a super cheap fork is likely made with cheaper materials/components, and as such may wear out faster. I don't have any personal experience with the XCT, but I'm also willing to bet it's considerably heavier than a fork you'd get in even the $100-$150 price range, its preload feature barely does anything, and it will eventually become really saggy or just plain lock up. This happened to me with the cheapie RST fork I was using on the first iteration of my frankenbike.