There are scripts available for migrating OpenACS 3 bboard data to OpenACS 4 (thanks to Musea) but ... ACES bboards are unrelated to the [Open]ACS 3x standard bboard.
So those scripts won't help.
Just thought I'd point this out before someone not realizing this misinforms Tracy that such scripts are available ...
I do think the Tcl script approach is best. The bboard migration scripts work very well.