You can run Eclipse using the VM from IBM Developer Kit for AIX versions 
1.4.2 and 5.  The IBM Developer Kit for AIX can be downloaded from:
http://www.ibm.com/developerworks/java/jdk/aix/service.html

To run Eclipse on AIX, you must ensure that your AIX install includes the 
necessary filesets and service updates.  Please use the following command
to determine the service level of an AIX fileset on your machine:
	lslpp -l | grep FilesetName

Please see the section below that corresponds to your AIX release.

All AIX releases:
    Fileset X11.adt.lib must be installed (this is available on the AIX
    installation media).

AIX Version 4.3.3:
	For fileset X11.base.lib:
		If service level < 4.3.3.79, you must apply APAR IY27694 
	For fileset X11.motif.lib:
		If service level > 4.3.3.81, you must apply APAR IY41939 

AIX Version 5.1:
	For fileset X11.base.lib:
		If service level < 5.1.0.25, you must apply APAR IY27695
	For fileset X11.motif.lib:
		If service level > 5.1.0.36, you must apply APAR IY41942

AIX Version 5.2:
	For fileset X11.motif.lib:
		If service level > 5.2.0.0, you must apply APAR IY41944

IBM APARs can be downloaded from:
http://techsupport.services.ibm.com/server/fixes

There is a bug in the Oracle Java 7 64-bit JRE (b147) which may cause Eclipse
to crash (http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7070134).  
The crash can be avoided by using the -XX:-UseLoopPredicate VM argument 
(-vmargs -XX:-UseLoopPredicate).  Alternatively, you can use a different JRE.