Mooney has made more than 200 appearances for Skelmersdale in two spells and has also played for Warrington Town, Runcorn Linnets and Atherton Collieries.
Fosu-Mensah, 24, arrives having left Welsh Premier League side Llandudno last month.
The brother of Fulham defender Timothy, Alfons has had spells with National League and Northern Premier League sides including Southport, Ashton United, North Ferriby United and Marine.
They are both available for Saturday’s trip to Kendal Town.
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