Each of the feature codes, like DSER, brings in a set of capabilities. There is no point in enabling just a couple of features; if you're going to hack the scope, might as well do it all.
After the hack, your scope will identify itself as a DS1104X - the 100 MHz version of the DS1054Z
There will be 15 features enabled (which I won't list) including decoding Serial, I2C, SPI, increased memory depth, increased bandwidth, etc
This stuff is all over Google