3 way switch wiring

[Willybomb]

Gudday all.

I've got it in my head to re-house a Behringer GDI-21 and make the Tweed/Brit/Calif and Clean/HighG/Hot footwitchable.  As these settings are set from a 3way switch each I want to drop the Tweed and Clean from the options and use a stomp to go between each of these.

My issue is thus:

The switches used look identical to these ones:
http://parts.digikey.com/1/parts/973952-switch-slide-dp3t-pc-mnt-l-2mm-eg2305a.html

and the pinout is with 7 and 3 being common.

5   1

6   2

7   3

8   4

The positions are:
1 - 1 and 3, 5 and 7
2 - 6 and 7, 2 and 3
3 - 7 and 8, 3 and 4

Presuming Position 1 is Calif, and Position 2 is Brit, how would I go about replacing this switch with a stomp?  I presume I can leave Position 3 disconnected... I suppose I need to know what those pins are actually connected to on each pole...