You need to download all of the following

1)  Alpha 6.52 from Alpha's home site.
2)  Alpha 7.0fcN (either full or minimal) from this site.
3)  Alpha-68k-resources from this site.

Throw away ALL of Alpha 6.52 except for the actual 68k Alpha 
application.  Open it and the resources file in ResEdit/Resourcerer
and copy all of the resources from the small file into the 
application, REPLACING ALL DUPLICATES.  Save and quit.

Now replace the ppc-only application in the 7.0fcN folder you 
downloaded with the 68k-only one you just created.  Double click
on it to start.

-- Vince.

Note: One user has reported crashes with 68k Alpha 7.0 when using cmd-F 
or selecting 'Find...'.  If you experience this you may wish to try 
the above except using the Alpha-68k-fc3test.rsrc file from this site.
It may (or may not) help.

BIG NOTE:  If you have got the above working, why not upload a copy 
of the 68k-only application to Pete Keleher's ftp site so that others 
can benefit?  The 'up' directory at that site is writable and for 
exactly this kind of purpose.