Upgrading woes - Markaby

I have spent the afternoon trying to upgrade a once Radiant 0.6.4
application to the latest version of Radiant and Rails (2.3.4 is frozen
inside Radiant). I am having a familiar Markaby issue–the opening form
tags are not being rendered from my form_for builder.

I have learned that the concat method which is necessary for creating
custom form builders (which I have) no longer needs the proc.binding.
No worries, I sidestepped that issue.

My major issue now is getting Markaby working. I have had no issue
rendering my form_for from within an ERB template. It’s only from
inside a MAB template that it fails. I get the contents of the form
rendered, but not the opening form tag. I spent quite some time after
discovering Markaby reworking dozens of ERB forms into MAB forms and now
it looks like I may have to backtrack and avoid Markaby altogether just
to complete the upgrade.

Has anyone gotten Markaby to work with the latest Rails? Particularly,
the handling of the form_for issue?

I have an only copy of the Markaby plugin which mostly works (all but
the form_for rendering). I have tried to grab the latest copies of
Markaby from github and from the gem, but those don’t seem to work.
They produce error messages.