You can replace the B/T controls with a filter and a Q switch, without any soldering - it's all modular, and the connectors are of the click-on type. So it should be an easy thing to do.
You may need a spacer to mount the Q switch in the hole where the B or T pot used to sit - except if you have an older Epic, which has pots with a narrow shaft. In that case you need a filter pot with the narrow shaft.
Another option would be to add a filter to your BT controls, but you'll need to drill two holes, and the control cavity needs to be large enough.