Actually, the developing reagent (in the case of split D-23 and/or Stoeckler) is Metol. Since Metol requires sulfite as a preservative and sulfite is a weak alkali (and thus an activator), the "A "solution will develop film all by itself. The Stoeckler "B" bath is just Borax and water.

In principal, you can split nearly any developer into the developing reagent (in some form of preservative solution) and the alkali.

Here is the recipe for a Diafine-like split Phenidone-Hydroquinone (PQ) developer:

"A" Bath

Boiled Water @125 degrees 750ml
Sod. Sulfite 35.0 grams
Hydroquinone 6.0 grams
Phenidone 0.2 grams
Sod. Bisulfite 6.0 grams
Boiled Water to make 1.0 liter

"B" Bath

Boiled Water @125 degrees 750ml
Sod. Sulfite 65.0 grams
Sodium Metaborate 20.0 grams
Boiled Water to make 1.0 liter

Can be used between 68-80 degrees
Do not pre-soak.
Soak in bath A for 3 minutes.
Move to bath B for 3 minute soak
Do not rinse in between baths.
Do not use acid stop bath; use water rinse.
A non-hardening fixer is recommended.

Both the "A" bath and the "B" bath can be reused.

You can change the dilution of the "A" bath for one-shot use to develop films like Kodak Tech Pan.

You can also change the alkali in the "B" bath to increase and decrease the contrast and apparent grain. For example, you can replace the metaborate with carbonate or with borax.