The process for getting out of the Army depends on various factors.
But from the information you have provided it sounds like your friend
1) is still in the first 180 days of his service and 2) is still in
advanced training.  These two elements are very good as it means he
may be eligible for an Entry Level Separation.

Most of the text below has been extracted from pages on  GI Rights Hotline site:
http://girights.objector.org/

They also have a 1-800 number that you or your friend can call with
questions about getting out of the Army (but they ask that you first
read through the information on their site):
http://girights.objector.org/contact.html.

If your friend is still in entry level status and *starts* the
discharge process during that time, then he may be able to get an
Entry Level Separation.  The separation/discharge does not have to be
completed during entry level status, just started in that period. 
But here is a summary of the "out":

"If you are in entry level status and cannot--or will not--adjust
socially or emotionally to military life or cannot meet the minimum
standards of your training program, you may be eligible for
separation.
Entry level status is the first 180 days of active duty.
...  While there is no official way to apply for this separation, you
can bring problems to your commanding officer's attention, in the hope
that your commander will consider your separation to be in the best
interest of the military. But you'll need to act fast. In order to get
this discharge, your commanding officer must start the discharge
process while you are still in entry level status."
above text from "Entry Level Performance and Conduct":
http://girights.objector.org/gettingout/entrylevel.html.

"You will receive an Entry Level Separation if separation processing
is begun while you're still in "entry level status" (generally, the
first six months of active duty). This uncharacterized separation is
neither honorable nor less then honorable because you have not been in
the military long enough to develop a record. With an Entry Level
Separation, you are not entitled to the usual veterans benefits."
above text from "Things You Need to Know About Seeking a Discharge":
http://girights.objector.org/gettingout/needtoknow.html.

The specific/official reasons for seeking a discharge may be best
known to you and your friend, but...

"Be creative with the various criteria listed in the regulations. Some
are so broad and vague that any number of circumstances could come
under them. For example, "failure to adapt to the military
environment" or "cannot adapt socially or emotionally to military
life" could cover anything from a budding conscientious objection to
war to a strong aversion to military life."


PEACE-OUT
"Unfortunately, you cannot directly request an ELS, but you can
present your problems to the command so that the process will be
initiated. A first step in approaching the command can be for you to
tell your problems to a chaplain and try to get a referral to the base
counseling center. You can also request a meeting with the commanding officer to discuss your difficulties. You can approach your command in the role of a patient presenting his or her problems. Encourage others familiar with the situation (such as a clergy member or chaplain, lawyer, doctor, or social worker) to approach the command. If possible, find a friendly military psychiatrist, medical officer, or chaplain to help bring the case to the command's attention."

"The military grants the greatest number of ELS discharges during
basic and advanced training. Therefore, this discharge is more likely
to be granted before training is completed -- when commanders are less
likely to be penalized for "losing" a soldier."

Above paragraphs from "Fact Sheet: Entry Level Performance and
Conduct":
http://girights.objector.org/gettingout/entrylevelfacts.html .

A listing of and links to the various actual Army discharge
regulations (in PDF format), can be viewed at:
"Army Discharge Regulations":
http://www.objector.org/helpingout/army-regulations.html.

A somewhat related site:
"Central Committee for Conscientious Objectors":
http://www.objector.org/

You may also want to see if your local library has the following book:
"Helping Out: A Guide to Military Discharges and GI Rights" by Alex
Doty:
http://www.objector.org/helpingout/description.html

It  is strongly recommend that either you or your friend call the GI Rights Hotline so that you can fully discuss the full story that you did not wish to get into in your question text here.

There have been a number of GI's who have gone  AWOL rather than fight what they consider an illegal and immoral war. The number has not been released by the DOD, but estimates range from 8,000 to 10,000 have gone AWOL.


Be warned, however, that a federal warrant, which remains valid for forty years, "is issued the moment a soldier crosses the line between absent without leave and desertion. A soldier who does not show up for duty is classified as AWOL for 30 days. After that, he or she becomes an official deserter. During a time of war, the 30-day grace period disappears."

You can read more, and listen to an interview on the subject:
Mission Rejected: U.S. Soldiers Who Say No To Iraq
GETTING OUT OF THE MILITARY ONCE YOU'RE IN (IT ISN'T EASY, BUT IT CAN BE DONE)