Silicon Chip magazine did a really good project writeup on setting up an off the shelf toaster oven for this kind of work. There's probably oodles of other writeups around the web.
Short version of theirs: stick a slab of aluminium in there for your board to rest on, attach an accurate and fast temperature probe (like a thermocouple and a multimeter) to the slab. Do a couple of test runs without a board in there and graph the temp vs time. If you're in luck as they were, when you turn the oven on full, it heats up nicely within the "reflow curve xxx mentioned, then when it hits the bottom of the recommended temp range you can turn it off and it'll coast up into the flow zone, peak and then cool down at about the right rate to stay inside the curve. If the delta-t strays outside the curve (or for extra geek points) add a micro to automate it.
This is also a good way to recover useable SMT components from old or dead boards, aka "bake and shake" :lol: