Unclear how to create new timestamped plugin migrations

So excited the migrations issue has been resolved.

My issue is, I’m working on a plugin, and I want to add a new migration
in the plugin directory. Per the new migrations.rb docs (see snippet at
end), my migrations should be timestamped. In a rails app, I can
‘script/generate migration xxx’, which gives me a timestamped file in
the migrations directory. But it’s not clear how to do that in the
context of a plugin. Note i’m not talking about “script/generate
plugin_migration” (which is deceptively named in this situation).

[aside] Also, I can’t seem to generate rdoc for engines – it flakes on
all the extensions (Skipping require of dynamic string:
“engines/rails_extensions/#{name}”) and I’m not sure how to manually
generate those docs. Since the online api docs aren’t updated yet, I’ve
got to read the docs inline in the code (horrors)!

vendor/

|

plugins/

|

my_plugin/

|- init.rb

|- lib/

|- db/

|-migrate/

|- 20081105123419_add_some_new_feature.rb

|- 20081107144959_and_something_else.rb