might be too obvious but did you create/enable extras-devel repository in app manager? if not, enable it, and you'll find version 40 there.

Name: extras-devel
URL: http://repository.maemo.org/extras-devel/
Distribution: fremantle
Components: free non-free

as is always the case, make sure you understand what the risks are with 'extras-devel' repo. (re)visit the reflash wiki just in case you need it. a good habit is to disable the repo after download/install. have fun