To edit the bands requested as part of UE capability, edit the file found at srsenv/src/stack/rrc/rrc_ue.cc.

You can set the bands on line 1086 and 1095 -- about 15 lines in to the send_ue_cap_enquiry function.

After doing so, run:

mkdir build
cd build
cmake ../
sudo make -j$((`nproc`+1))
sudo make install
sudo srsenb

This builds and launches srsRAN's eNB. Config files can be edited normally (usually in /root/.config/srsran/...).