1. How do you start winding? Where do you put the first wire? Pin 1?
one approach is to pick a commercial inductor and match it. There are two sources of well documented tapped commercial inductors Carnhill and Chrion on the white market, there may be others. They both offer pinouts on their site. Carnhill works in 2 different sizes of pot cores and in RM7, Chrion work in RM8 cores. The white market thread Chrion runs has a pinout for his inductors. The design guide PDF on carnhill site has their pinouts.
Sowter makes some, and I think generally uses wire leads rather than pins, but I think they document the colors on the site.
Anyway, I have done RM7, RM8 and Pot core tapped inductors and I usually try to find the closest Carnhill inductor, make a little 1" x 1" perfboard holder and jumper or wire the core to the appropriate pins (I use pins from DSub 25 pin male pins which work well and are crimpable on top to hold the wire while I solder. It probably doesn't matter, but I like the idea that I can use the inductor in a PCB that calls for a carnhill if I don't use it in the project I am doing.
2. Which is the coil ground? Is it the last piece of wire you got left? Is it the fist piece?
As far as I can tell the coil ground is generally a separate pin. In the case of the RM7 RM8 etc it is usually one or both of the clips. Since the ferrite core is not electrically conductive you can't really ground it but I have seen pics in carnhill that they solder a wire from one clip to a copper foil strip wound around the coil (but I don't think you want to allow that foil to make a loop (I keep it open with tape) for shielding. i don't know what effect this has. You could also wind a single layer around the coil with one open end and ground that (I have seen that done) think of it as a long spiral shield, open on one end. I think these are electrostatic shields.
3. Which is the core ground?
You pick, but carnhill calls it out and provides photo's of what I am talking about in their PDF design guide.
4. How do you wire it in parallel? Do you go (22mH/69mH) + (ground) to get 47mH?
inductors in series add (opposite of capacitors) so I think a 22mH in series with a 69mH is a 91mH. But on a tapped inductor it doesn't seem to work that way because the inductance is proportional to the square of the number of turns so (as your link reference mentions) you can have a 69mH tap and a 91mH tap, but don't expect them to be 22mH apart. As luck (or design) would have it, the pultec (and g-pultec) design just calls for different inductances from the "START" of the coil, so the "between" amounts don't matter (they will be correct i you use separate inductors but they won't if you use a tapped coil but both will do the exact same job (if the inductance matches) regardless. I believe you are using "ground" in this case incorrectly. A tapped coil has a "Start" then it has tap 1, tap 2, tape 3 etc. You can ground anything you want, but the ground marked on the Carnhill design guide is just a link to the frame or shield of the inductor. Their tapped inductors are measured from a start pin to various other pins.
5. How do you work it into the G-Pultec PCB?
I have built a pultec passive EQ section (using my own transistor buffers) but I have not built one using the G-Pultec PCB. but I believe the PCB calls for separate inductors. in this case using leads and jumpers from your DIY tapped inductor you could connect to the PCB and it could work just fine (a bunch of inductors in series looks like a tapped inductor and is just what the G-Pultec and Pultec EQP-1 schematics call for.
Thanks,
Alain
