With no bathtub for soaking, you will have to use a basin for your feet, and take the ES and baking soda that way. You can use this footbath, and soak for 10-20 minutes, adding more hot water for comfort.
You might like to visit Moreless' forum--if alkalizing/detox via ES and baking soda is your main interest.
Fixing the terrain on the inside, with fruits and vegetables
and no processed foods or drinks will do a LOT.