In relatively simple terms you can group honda ECUs for B and D series engines into 2 types:
OBD1 and OBD2 (On Board Diagnostic Version 1 and 2)
OBD1 is everything from about '92 to '96 and OBD2 from '96ish on, there are 2 versions of OBD2 (a and b) but we are more interested in OBD1.
The Code in the ECUs is 99% the same between OBD1 and 2 so to a point they are interchangeable, its pretty simple with a wiring conversion harness to put an OBD1 ECU into and OBD2 car. The clever bit of the P28/P30 and similar ECUs is honda put a reserve part on the ECU so you could add a chip with a custom map on there. No idea why they did this but it makes chipping them awfully easy and incredibly flexible.
So the cheapest option is to take your P28 or P30 ecu (you can use many different ecus as they are a common board, even the P06 from the non vtec d series works, you add the vtec circuitry to the board and enable it with the programmable chip), and just add a programmable chip, then get your local tuning company to write you a suitable map on there (you can tune on a rolling road and get it all spot on).
the next step is to use something like the ostrich. the ostrich plugs into the ECU where the new chip would be and uses your computer to emulate what the chip does, once you have your map sorted on the ostrich and computer you can burn a chip.
The Hondata and Moates Demon are a chip emulator like the ostrich, but they will save the map on the unit in the ECU, you only have to plug your computer in to make changes, they also datalog and have extra inputs and outputs.
Does that help?