i have been plodding through the wayback machine.
one interesting link i found relating to v3+:
https://web.archive.org/web/20150923...r=asc&start=20
According to this, v3+ sdk seems same a a v5 sdk.
A suggestion is, try to contact Buggins. He may be able to help.
(github, sourceforge etc.,)
https://github.com/buggins
Failing which,
another suggestion is to create your own toolchain:
something like this, it deals with the exact same processor of the v3+.
https://www.sachinsharma.com/2010/12...hain_7883.html
(might be a real long shot this one)
On other thoughts: why try to develop for such an ancient device?
something like a BQ Cervantes, would be far more easier.
It is supposedly open source and sourcecode etc., all available in github.