Well an LPB1 is a transistor boost and putting a simple tone control at the input will set the frequencies being boosted. Look how the Range pot works in the Red Rooster here:
http://tagboardeffects.blogspot.co.uk/2011/11/dam-red-rooster-vero-layout.htmlYou take the input to a pot and then have two wires going out of the pot to two separate input capacitors, a 5nF and a 2.2uF. So in the extreme counter clockwise position the signal is routed through the 2.2uF cap which lets a lot more bass frequencies into the effect, in the extreme clockwise position the signal is routed through the 5nF which cuts a lot of the bass frequencies out and so is more like a treble boost.
http://2.bp.blogspot.com/_y7gcfRKQFgA/S6VnFIga11I/AAAAAAAAAIY/beERCO9AO_A/s1600/EHX+LPB1.pngRemove the 100nF input cap in the LPB1, add an extra column, and then add the Red Rooster Range pot complete with 5nF and 2.2uF cap and you've got exactly what you're asking for.