Can you show a picture?
The outlet should have a line side and a load side. Each side has a hot and neutral.
From the breaker, a power wire goes to line hot. Neutral from supply goes to line neutral.
From load hot, go into the first switch. Then through any other switches in series. Your x10 switch should be on the load side before or after the relay. If you're only using the X10 switch for the light, you don't have to go through the relay.
Load neutral from gfci goes to light.