Okay, I said there must be an easier way to do this so I Googled it and found this. This looks like a knit 2 tog tbl to me. Then Imbrium sent me a link to this, which is how I've been doing it but is a royal pain in the ass. They are, of course, completely different.
Further searching lead me to The Irish Ewe who said to twist each stitch and then purl through the front. This sounds good. You would go into each stitch from the back and turn it, then put them back on the left needle and purl.
A little further on I came to this from wiseneedle:
"The conventional way is to take your right hand needle and stick it through the back loop of the next two stitches on your left hand needle. But stick it through such that the points of both needles are headed in the same direction. Then wrestle the yarn into place and make a pseudo-purl motion to work the two stitches together, ending up with a decrease that when viewed from the back, is analagous to a SSK (slip-slip-knit decrease).
There's a cheater's way to do it, too. You need a DPN or cable needle. Slip the next two stitches together and purlwise onto the DPN or cable needle. Now pretend the DPN is a giant helicopter rotor. Rotate it 180 degrees clockwise. Now slide the two stitches from the DPN back onto your left hand needle. Purl them like you normally would, ignoring the weird twist you've just made in them."
This is the same thing that The Irish Knitter said except you use a cable needle. I will try both this method and The Irish Ewe's and see which works best for me. I have a lot of experience at cabling but I'm not sure I want to fool with another needle.
Thanks, Imbrium, for the help.