Most biscuit joiners will let you either take the fence off or fold it up to 90 degrees (e.g. the Makita PJ7000 - I own this - has a removable fence, while the Dewalt DW682's fence folds up to 90 degrees). After this, like the other answers say, the T joints are fairly trivial. Biscuit joints lend themselves very well to this, in fact.
There is a great how-to by Ken Collier of The Family Handyman here. Reproducing some of that (it uses shelving as an example but these same marking and cutting techniques can be applied to anything):
This is where joinery shines: the T-joint, where a fixed shelf meets the sides of a cabinet (Photos 1 – 3). The sideways wiggle room that biscuits give you allows you to get the edges of the shelf and the sides perfectly flush, and the case looks good, with or without a face frame, both inside and out. And since the glue is all on the biscuits, there’s rarely any squeeze-out to clean up.
The process for making a T-joint begins with marking on the edge of the sides where the top of the shelf should be. Stand the shelf in position and mark the biscuit locations. Then lay the shelf on its side, lined up with its location mark. Clamp the side and shelf together and to your bench, with the edges flush to each other. Now cut your biscuit slots, first in one piece, then in the other. Do the other side of the cabinet the same way, making sure the shelf is oriented the right way: front to front, bottom to the bottom.
There is also a video on that site, if you scroll down to the Making Cabinet Boxes With T-Joints section, at the bottom of it you will find the video.
Another more to-the-point video can be found on the Lamello site. There's a series of product demonstration videos on that page, the one you want is titled Dividing Panel Joint and is currently the 4th one over in the series.