Don't worry. I personally cheat in video games (ever since I discovered the game genie), and I say its none of no ones business if they do or not. Its not going to effect those hardcore gamers out there that don't unless its a online game. Enough of that rant.
The reason why there is no cheats for the game is because the Sega CD that is being emulated, does not have any cheat support. So a walkthrough of the fight will be a good alternative.
Taken from
http://www.gamefaqs.com/console/segacd/file/587964/5247
BOSS STRATEGIES: BORGAN
IMO, this is the most difficult battle in the game. His Gravity Bomb
spell deals almost 200 HP of damage to every party member (enough to
kill Lemina with one hit if she's at a low level). He's also surrounded
by three orbs, and he is impervious to your attacks until you destroy at
least one of them. The orb in front of Borgan attacks the party
members. The orb behind him casts healing spells on Borgan. The orb to
Borgan's side casts the Magic Shield spell. Whenever his cane is
pointing towards you, Borgan is going to cast a random elemental spell.
And when his arms are stretched out to his side, Borgan's going to cast
Gravity Bomb. Make sure Jean (or Hiro) is equipped with the White
Dragon Crest and have her (or him) cast WD Protect whenever you see that
Borgan's about to use the Gravity Bomb spell. Destroy the orbs first,
then attack Borgan. Have Hiro cast Poe Sword, Ronfar cast Rest Litany
every round, and have Jean use Haduken (if she has the Blue Dragon Crest
equipped, have her cast Blue Dragon Vigor and attack the next round).
Borgan tends to reflect Lemina's attack spells, so she is pretty useless
in this battle. Have Lemina cast Magic Shield, and have her use Silver
Lights or Dover Nuts whenever necessary. Lucia, as usual, contributes
with the occasional attack spell (although Borgan sometimes reflects
these spells too).