All you need to do partial mash is another pot to mash in, a pan to heat water in and a kitchen strainer. I just used our pasta pot to mash in and a regular saucepan to heat sparge water in.
Heat your mash water in the pasta pot while you warm your oven up to it's lowest temp. When your water is at the right temp, throw in your grains and stir them up well. Check the temp and adjust with a little hot or cold water if you need, then pop it in the oven and turn the oven off. The residual heat will keep your mash pot warm longer than sitting on the stove.
Give the mash a stir about halfway through and run the oven for a minute or so if it needs to warm back up.
after about 45 minutes, heat up some sparge water in the sauce pan. At 60 minutes, pull out the pasta mash pot and dump it through the strainer into your brew kettle. Dump the grains back in the pasta pot and pour on the sparge water. Give it a little stir and pour that back into the brew kettle through the strainer again. Do it a third time if you want to double-sparge.
That's it! Easy as pie! I did it that way all the time before I broke down and got a beverage cooler to use as my partial-mash tun. It works great as long as you don't go overboard on grains. When I started going over 3 or 4 lbs it got to be too much to handle with a pasta pot.
I think DeathBrewer's method can handle larger amounts of grain if you need, but with a cooler it's SUPER easy. (nod to the Gnome)