The backported dtrace packages, when it is ready, will be installed in /opt/SUNWdtrd. The Makefiles need to be modified to find the dtrace compiler program at this location when running on versions of Solaris < 10.
Remove the workarounds for dtrace bug 6254741 in sharedRuntime.cpp and synchronizer.cpp, when the dtrace bug is fixed and tail-calls aren't mauled. The workarounds are noted in the comments.