That I'm aware of, SureFire only retail straight cable tape pressure switches.
There is no tape pressure switch for the E Series. However, SureFire's ScoutLight WeaponLights do have a tape pressure switch TailCap although I do not know whether it will fit the E Series even though the KL4 is shown on a ScoutLight on page 62 of the SureFire Guns&Ammo Combat Tactics 244 (Vol 1, No. 2)
A dedicated forend WeaponLight would seem one of the best options, another would be a forend rail and a WeaponLight fitted with a Clickie TailCap (such as the M952C).
In 2004 the ScoutLight and X200 will be released. The both will have a number of different switching options.
Al