Newbie problem building sablevm-sdk-1.12

I'm trying to build the shiny new sablevm-sdk-1.12 on 5.4 (actually, its
been installed by PCBSD because I'm lazy about configuring X etc) - but I
have a set of 5.4 release CDs I can use to get extra packaged bits.  Ports
are harder because I have time to do this on the train, with no internet
connectivity.

./configure went OK.
build-early (jikes) went OK
build-early (fastjar) went OK

However in configure-main (sablevm) its failed with:
checking for lt_dlinit in -lltdl... no
***ERROR: libltdl is missing

I've spent 20 years as a professional C++ programmer on SunOS and MS
systems - but I have no idea about auto-confiscate and libtools. :-(

So ... help!

Is it straightforward?

Fixes to work around threading and compilation I can handle, but I'm out of
my depth with this 'magic' stuff.

James