[Elecraft] Two Inputs for PTT ?

[paul ecker]

Hope I am not expending my quota of dumb questions but hey I  am new. Got my Tx foot switch plugged into the back panel PTT jack  and it works fine. My next project is to get my SignaLink USB up and running with the K3. I know I can do lots without it but I would like to not use the PC sound card. So here's my problem- I got the SLCABK3 cable from Tigertronics which has 3 leads on radio end: Line In, Line Out and PTT. But the my PTT jack  is used already. What it i were to make a Y cable allowing two PTT inputs to the K3. Signalink only used for digital modes, so it's an either or situation, both would not be used at the same time.
- Is this doable, not going to harm the K3? anyone else encounter this problem?
73 & tnx 
Paul kc2nyu