Gut instinct says no, but it depends on the routeing guide. A fares check won't come into it as Liverpool and Preston are both routeing points.
The shortest route is via Ormskirk at 27.75 miles, and Liverpool to Manchester (Victoria) alone is 31.75 miles, which is more than 3 miles further, so you can't use the "shortest route" rule.
Mapped routes can be found on maps CP (via Ormskirk), KW (via Warrington and Wigan) or XV (via Huyton and Wigan), none of which get anywhere near Salford, so you appear to be out of luck unless you can find a direct train from Liverpool to Preston that stops at Salford.