Here's the command line parameters I use to deinterlace 60i to 60p.

If you use PD10 to slow down a 60i clip, it throws away half the fields, and you effectively only slow down 30 fps source footage

ffmpeg -i myinterlacedfile.m2ts -vf yadif=1:0 -vcodec libx264 -vpre hq -acodec copy -copyts -threads 0 -b 22000k "myprogressivefile.mp4"

The tricky part with ffmpeg is getting the presets to work.

You can download a bunch of them here:
http://www.mediasoftpro.com/aspnet-x264-presets.html

The presets must be in %home%\.ffmpeg

C:\ffmpeg\presets\.ffmpeg>dir
Volume in drive C has no label.
Volume Serial Number is 902B-83FA

Directory of C:\ffmpeg\presets\.ffmpeg

03/31/2012 06:59 PM <DIR> .
03/31/2012 06:59 PM <DIR> ..
05/18/2011 03:37 AM 43 libx264-baseline.ffpreset
03/19/2010 02:05 PM 304 libx264-default.ffpreset
03/19/2010 02:05 PM 313 libx264-fast.ffpreset
03/19/2010 02:05 PM 313 libx264-faster.ffpreset
03/19/2010 02:05 PM 313 libx264-faster_firstpass.ffpreset
03/19/2010 02:05 PM 322 libx264-fastfirstpass.ffpreset
03/19/2010 02:05 PM 313 libx264-fast_firstpass.ffpreset
34 File(s) 9,427 bytes
2 Dir(s) 5,368,791,040 bytes free

C:\ffmpeg\presets\.ffmpeg>echo %home%
c:\ffmpeg\presets

Assuming you save your presets in the same spot I did:

You can set the HOME variable using the following command line function:
setx home c:\ffmpeg\presets
(this takes effect for new command line windows only, not the one you just entered. So close it out and open a new window)

What ever folder you specify as HOME, the presets must be inside a folder .ffmpeg inside that folder.
It took me a long time to figure this out.

Attached are the source 60i footage, and a low bitrate 60p version (low bitrate to save download time)

The yadif filter does quite well at deinterlacing and "doubling" the frame rate. Technically 60i is really 30i (two fields per frame)

Download both clips, slow then down in powerdirector to 10% and you'll see what I mean.