I have the Eclipse run in the effect loop of a Sansamp PSA and select patches with a midi pedal. If I want to control the effects in real time, for instance, mix an effect from zero to 100% wet or speed up a tremolo, or add depth of reverb, how is this done, what type of pedal do you recommend, and does it plug in the footswitch jack or is it midi?
You can use Pedals conncted to the Pedal 1/2 inputs on the rear panel AND/OR pedals connected to/built in a MIDI pedalboard. The firsts will be seen as Pedal 1 or 2, the seconds will need to be programmed in the MIDI pedalboard to send out MIDI CC messages.
For how to patch parameters to external controllers (hardware & MIDI) and how to setup things in this area you should refer to Eclipse user manual, as it offers a very detailed section on the topic, "Modulating Parameters Via the modulation block: LFO, ADSR, Envelope, MIDI, Pedals, And More", starting from page 40 of latest V3.51 Release manual. It will be very helpful to follow the complete instruction provide there.
The pedal needs to be a simple volume pedal, wired w/a stereo 1/4" jack, with a 0-5 volts value. Most Roland, Boss, Bespeco, Proel pedals will work and can be calibrated on Eclipse to properly cover the expression range.