How should I guy wire my mast on my roof?

Hello,

I need to add some metres to my mast - I was thinking of going up 3 metres above peak, and with a 25db grid up there, I worry it might one day come crashing down especially after watching the sway/twisting action after these storms.

So I was thinking of running a set of 4 guy wires down - anchoring to the edges of my tiled roof. I have looked around, mainly at the common hardware places, for the pieces but cant find any way to anchor to the roof.

How do the other airstream members achieve this?

Also can the hills telomasts extend only partially (i.e. 6m only go up 3m?).

TIA. I've been dealing with crappy signal for too long and hope to do something about it :)