Move back to Myth 0.21

[fastie81]

Hi guys

Can I move back to 0.21 without reinstalling my system?
I have a problem with my HDHomerun DVB-T that looks like will not get fixed in 0.22
here is the ticket.
http://svn.mythtv.org/trac/ticket/7624
Can this be done and if so could someone put a wiki together or point me to some info?
Thanks
C