Almost done. I have installed "presencevnc" but when trying to connect :
$ presencevnc vnc://192.168.0.101:5900
I get :
"Failed to initialized GnuTLS: The gcrypt library version is too old.."
about to quit

The problem is libgcrypt11 from Harmattan is old, v1.2.0.

I have downloaded from rzr's repository the files below installed with dpkg :
# dpkg -i libtasn1-3_1.4-1_armel.deb
# apt-get install libgcrypt11
# dpkg -i --force-all libgnutls26_2.4.2-6_armel.deb
# dpkg -i --force-all libvncserver0_0.9.8.2-2_armel.deb
# dpkg -i presencevnc_0.0.0-0~rzr1_armel.deb

So it seems the solution is simple, to avoid the warning/erros messages :
" libgnutls26 depends on libgcrypt11 (>= 1.4.2); however:
Version of libgcrypt11 on system is 1.2.0-11.1osso5+0m6.
libgnutls26 depends on libgpg-error0 (>= 1.10); however:
Version of libgpg-error0 on system is 1.6-1.1+0m6."
we need libgcrypt11 (>= 1.4.2) and, maybe, libgpg-error0 (>= 1.10).

I have downloaded debian armel libgcrypt11 v1.4.5 but I can't install, conflicting with the MeeGo Harmattan version :
# dpkg -i libgcrypt11_1.4.5-2_armel.deb
Aegis rejecting libgcrypt11_1.4.5-2_armel.deb: package 'libgcrypt11' already installed from 'com.nokia.maemo' -- not replacing it from unknown origin
aegis aborting dpkg -- all listed package files rejected
Compilation failed in require.