You'll want to get 6.3a, if you don't already have it. There are two methods listed at the top of this forum. In both, the correct procedure to disable scrambling is listed.

TechLore Blog

HR10-250, Samsung SIR-S4120R, SIR-S4080R, 2 Philips DSR704s (one connected to a Slingbox A/V). One box used the "Zipper"; rest used PTVnet to enable networking features.

http://www.dvrplayground.com/article/12503/

I wrote that for 3.1.5f, but added a comment under it for 6.3a (what you wrote above is correct for 3.1.5f).

TechLore Blog

HR10-250, Samsung SIR-S4120R, SIR-S4080R, 2 Philips DSR704s (one connected to a Slingbox A/V). One box used the "Zipper"; rest used PTVnet to enable networking features.

I fixed the link above. For some reason, the wrong url got copied/pasted. The link above points to an extraction article.

TechLore Blog

HR10-250, Samsung SIR-S4120R, SIR-S4080R, 2 Philips DSR704s (one connected to a Slingbox A/V). One box used the "Zipper"; rest used PTVnet to enable networking features.

I'm just wondering about this:

That will only be there if the Zipper or rbautch's enhancement script was previously used on the HR10-250. The verbose post I made didn't show that, since that installation didn't have either of those.

As a warning (until it's fixed), don't use TiVoWebPlus to set up a Season Pass with 6.3a; doing so could make your Now Playing List not work (clicking on a recording does nothing). 

TechLore Blog

HR10-250, Samsung SIR-S4120R, SIR-S4080R, 2 Philips DSR704s (one connected to a Slingbox A/V). One box used the "Zipper"; rest used PTVnet to enable networking features.