I found a paper by Li, Jiao and Chen on the solubility of SO2 in several solvents, including DEA. The title of the paper is "Solubility of sulphur dioxide in polar organic solvents". Unfortunately, the paper is not complete enough to be useful. It gives solubility at several temperatures, but it does not specify what the partial pressure is for SO2 equilibrated with the liquid. This means that the data in the paper is useless in its present form. I am actually surprised it got past the peer review process.
SO2 (which is a gas) can be bought in cylinders. I believe HBr (which is also a gas) can also be bought in cylinders. In principle it should not be too hard to build an apparatus that would allow SO2 and HBr to be added to DEA. Of course, good safety practices would need to be followed. On approach would be to treat DEA in two separate fractions, one for SO2 and one for HBr and then combine the two solutions in the proper proportions.