Hello again!

Found the solution. Newer Linux kernels 2.4.x are supporting
files larger than 2GB. To check for that support one should include
  AC_CHECK_FUNCS(llseek)
  AC_CHECK_FUNCS(lseek64)
calls in configure.in [btw. there is a (wrong?) line concerning "man/Makefile"
in at the end of configure.in which sould be erased!] 
for example like this:
[..]
### Check size of long and long long.
AC_CHECK_SIZEOF(long)
AC_CHECK_SIZEOF(long long)

AC_CHECK_FUNCS(llseek)
AC_CHECK_FUNCS(lseek64)
[..]
C_OUTPUT([ Makefile
src/Makefile
libtest/Makefile
# man/Makefile
templates/Makefile
html/Makefile
src/swf/Makefile
])

Run autoconf (Version 2.55!) to generate the new configure script out of the
patched configure.in:

$ autoconf

After running ./configure you are lucky 
to see something similiar to:
$ ./configure
[..]
checking for llseek... yes
checking for lseek64... yes
[..]

If these tests fail you need to upgrade your kernel respective libc... [after
that proceed here ;-)]
If the tests succeed do :
$ export CFLAGS="-DLARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64"
$ ./configure
$ make
$ make install

to build you an httrack which is capable of cache files larger than 2GB.
[The exported compiler flags yield the substitution of the "old" 32Bit file
operations by their 64Bit counterparts.]

Tested on SuSE 7.3 and RedHat 7.3.

Great thanks to the developers of httrack for using the standard file access
API and for this fine programm.

Happy compiling!

Volker