tortoiseHg and tortoiseSVN local repositories on Windows

[Snidely]

I would like to switch from tortoiseSVN to tortoiseHg, and some of the
files are in a TSVN local repository ... what is my best option for
moving the files over while preserving history?   I've added the
hgsubversion extension, but the clone command hg clone svn+file:///c:/
my/localsvnrepository reported "not found", and hg convert file:///...
brings up a help screen because convert isn't recognized.

I haven't seen this issue in the quick googling I've done, and it
doesn't show in the wiki articles I've seen on hgsubversion or
tortoisehg.

Thanks for your help.

/dps