From page 7 of the current ATP PTS
Use of the Practical Test Standards
[FONT=Arial,Arial]The TASKs in this PTS are for an initial airline transport pilot certificate, or the addition of a category, class, or aircraft type rating to an airline transport pilot certificate. All appropriate TASKs required for an initial type rating are also required for pilot-in-command proficiency checks conducted in accordance with 14 CFR part 61, section 61.58.[/FONT]
All TASKs are required, [FONT=Arial,Arial]except as noted. When a particular element [/FONT]is not appropriate to the aircraft or its equipment, [FONT=Arial,Arial]that element may be omitted. [/FONT]
[FONT=Arial,Arial]If the multiengine airplane used for the flight check does not publish a VMC, then the "Limited to Centerline Thrust" restriction will be added to any certificate issued from this check, unless competence in a multiengine airplane with a published VMC has already been demonstrated. [/FONT]
[FONT=Arial,Arial]Examples of element exceptions are: integrated flight systems for aircraft not so equipped, operation of landing gear in fixed gear aircraft,
multiengine TASKs in single-engine aircraft, or other situations where the aircraft operation is not compatible with the requirement of the element. [/FONT]
So basicly, you have to go through the entire PTS regardless of the type of test you're going for. You just omit the things that your particular airplane is not capable of. Just about every other PTS contains a matrix page that tells you which tasks to do for a particular test or addon rating, but the ATP doesn't have that.