I would suggest sticking with J2ME as the support seems pretty good and it doesn’t look too bad in terms of implementing an interface with the 3D api.
Take a look at the Developers Guidelines for J2ME on the sony/ericsson sdk page just under ‘Technical docs & Training’. In the getting started section 3/4’s of the way down this doc there is a section describing getting a 3d app working, have a look at it and it should give you an idea of the java level required.