Unfortunately your options are limited at this point. You didn't say how long ago he was sentenced, but the sentencing Judge has the option to recall a sentence within 180 days if he/she feels facts exist that warrant the change in sentence. You also said his appeal was already denied. I am not sure if you understand the subtle difference in a motion for a new trial (in the event you think that was his appeal - heard by the trial judge) or his appeal to the Court of Appeal in your district. That appeal process could take several years before a written opinion is delivered and published. If the verdict truly was affirmed by the Court of Appeal, your friends options would then be to petition a higher court to hear the matter, be it the California Supreme Court or to find Federal Grounds for Appeal and attack the conviction in Federal Courts. He or you, may also want to contact a lawyer and inquire about a Writ of Habeas Corpus and the possibility of investigating whether the lawyer who represented him at trial did so competently. If not he may have the ability to challenge the appeal due to incompetence of counsel.
Two other points is that you friend may not be in prison "the rest of his life". He will be eligible for parole after serving his 30 years and then will be entitled to parole hearings. If he does ever want to gain his release, he would be wise to follow the rehabilitation plan set out by his counselors and not get any 115's (prison violations) in his jacket. If he violates the rules of the prison or gets in fights, it will be very difficult for him to earn release. He also can appeal to the Governor for clemency or a pardon at some point if he adjusts well during his incarceration, however very few pardons are given.
Unfortunately with the new sentencing scheme for crimes where guns are used and even more so when people are shot during crimes, the law imposes stiff sentences and Judges do not have discretion to strike the punishments when those enhancements are found to be true. I hope this answers your question.