I've been looking for a way to do so for a while, so someone might be interested. (with a big help from http://moyashi.air-nifty.com/hitori/ !)

1) on a web page, create a link with the mapper protocol :
<a href="mapper://35.70574,139.75170">tokyo dome</a>

2) define this protocol in: /home/user/.mozilla/microb/user.js with:
user_pref("network.protocol-handler.app.mapper", "/home/user/bin/mapper.sh");

3) create the script /home/user/bin/mapper.sh:

#!/bin/sh
INPUT="${1##*/}
dbus-send \
--session \
--type=method_call \
--print-reply /com/gnuite/maemo_mapper \
--dest=com.gnuite.maemo_mapper \
com.gnuite.maemo_mapper.set_view_center \
double:${INPUT%,*} double:${INPUT##*,} int32:5

4) done!


(here, the zoom level is fixed at 5.)