I know that the Soviet Union were not participating in the Security Council affairs at the time, but I have read conflicting reports on Stalin's intentions towards American participation. Some of them that I read state that he deliberately boycotted it to allow the U.N.S.C. to draft a resolution to enter the Korean War, but other state that the U.S. took advantage of the boycott to draft the resolution against Stalin's wishes/intentions. Which one is more likely?
The Soviet boycott of the UN actually concerned China's seat on the Security Council. Although the CCP had taken power by that point, the expelled Chinese Nationalists still held that valuable seat, which the Soviets were not particularly happy with. This was actually the second separate boycott of the Council, coming after a failed resolution by the Soviets to expel the Chinese Nationalists, which was blocked by the West.
The Soviets actually had the opportunity to block UN intervention in Korea due to their own Security Council presence, but with them gone the Council was able to approve the resolution.
To answer your question, the second--that the UNSC and especially the US took advantage of Soviet absence to draft the resolution authorizing force in Korea--is in fact what happened.
Source: This Day in History, January 13