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[LOTR] How could Boromir use the ring against Sauron?

At the council of Elrond, Boromir suggests they use the ring against Sauron. How exactly did he think the ring could help them? Does the ring enhance your abilities? Did he think this because the ring helped Isildur during his reign, or was he under the rings influence already?
gpt
Boromir was already a great captain and leader, capable of rallying and commanding men. He was charismatic, loved by his people, and a great fighter in his own right. The ring would have enhanced these qualities while simultaneously corrupting his heart by increasing his nascent lust for power, and strengthening his ability to command. He would have become an incredibly powerful warlord, driving his men to great victories, but expending the strength of Gondor in so doing. it was noted in the histories that Boromir is said to have asked his father "How many hundreds of years needs it to make a steward a king, if the king returns not?" He was obviously power-hungry, even though this was tempered by his training and lineage. 

Assuming he could have prevailed against Sauron (which is doubtful -- his hotheadedness would likely have proved his undoing in a protracted war with Mordor. Boromir was very like to Eärnur, in his temper and mood; and it was Eärnur who caused the ending of the direct line of Númenorean kingship through his headstrong pride) he would have established a new Númenorean realm and might have begun to envision himself as one of the old Númenorean kings; possibly even taking the regnal name Rómendacil III, in honor of his  forerunners (although obviously not his ancestors) and his victories, but he would have needed to look for enemies, and would likely have descended into paranoia and tyranny, suspecting everyone around him. As he aged, and refused to share his power with anyone, plots would have developed in truth, and upon his death, whether by natural causes, war, or through assassination, Gondor would have splintered into rival factions led by warlords, whose squabbling would eventually lead to the breakup and end of Gondor as a power; and unless Sauron had been truly destroyed (and how would this have been achieved?), he would then return to wreak revenge upon his enemies, and the short-lived glory of the new Númenor  would end. 

Additionally, if he had dared to use the palantír, as his father did, he would not have had the strength of mind to resist Sauron -- look at how quickly the ring worked on him, leading to the breaking of the Fellowship. Even Denethor, as strong-minded as any man, was misled and corrupted by the visions of Sauron, even though he was not power-hungry or grasping. Boromir might have attained victory in arms over Mordor, but the victory would have ultimately led to the last downfall of Gondor.