A C lydian dominant is a G melodic minor (from C if you want to look at it that way). Or a G maj scale with a b3rd from the 5th of C7. Always. Lydian is always IV.
Or the major scale from the 5th of the chord. The melodic minor from the 5th of the chord is the lydian dominant.
This is the simplest way to find parent scales on the guitar. These are all lydian type scales.

[Edited by griphon2 on 02-09-2003 at 06:08 PM]