The former Pompey favourite has linked up with the non-leaguers after leaving Turkish side Şanlıurfaspor last year.
In February, Lualua, who made more than 80 appearances for the Blues during a golden three-year period, was keen to make a Fratton Park return.
However, a move failed to materialise and he has been without a club since his spell in the Turkish second tier.
The 36-year-old Dr Congo international scored 19 goals during his time at Fratton Park from 2004-2007.
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Since leaving the Blues, Lualua has played for Olympiacos, Al-Arabi, Karabükspor and Blackpool among others.