The new faces will become fully fledged members of the squad later in the week largely dependant on the ability of Kevin Morgan, Dafydd Jones and Chris Horsman to recover from respective ankle injuries.
Ospreys lock Evans is likely to confirm his place in the squad in place of injured regional colleague Brent Cockbain, who needs surgery to repair a hamstring. Bath scrum-half Williams should take up the third scrum-half berth in place of Llanelli Scarlets and Lions ace Dwayne Peel - himself recovering from surgery to an ankle injury.
Scarlets centre James returns to the international scene as cover in the backs for Dragons flier Morgan, Saracens prop Broster covers for his English premiership based colleague Horsman, who plies his trade with Worcester, and Cardiff Blues flanker Powell covers for the Scarlets' Jones.
"We have called in a group of quality players to train with the squad to compensate for the various injuries we have picked up and will take a decision later in the week as to who will join us full time," said Ruddock.
"Dafydd James comes to us for the first time since I've been in position as head coach, but he brings a wealth of experience at international level.
"We weren't completely happy with his form when he was with Harlequins last season, but he has been starting to look like his old self since returning to Llanelli and we are pleased to welcome him back into the fold.
"Andy Williams is a top quality athlete and we've had our eye on him for a while. Ian Evans is a young man who is a great prospect for the future and we want to see a bit more of him in the international environment.
"Ben Broster performed superbly for us on our summer tour of North America and so he will fit into the squad well if necessary and Andy Powell is a quality player who deserves his chance."
Dafydd James last played for Wales in the 43-17 defeat to New Zealand at the Millennium Stadium on 23 November 2002, he has 41 international caps and has played in three British Lions tests.
Dafydd James (Llanelli Scarlets), Centre
DoB: 24/07/75, Height: 1.93m, Weight: 96kg, Caps: 41 Wales, 3 Lions
Andy Powell (Cardiff Blues), Back Row
DoB: 23/08/81, Height: 1.94m, Weight: 114kg, Caps: Uncapped
Ian Evans (Neath/Swansea Ospreys)
DoB: 4/10/84, Height: 2.03m, Weight: 108kg, Caps: Uncapped
Andy Williams (Bath), Scrum-Half
DoB: 7/02/81, Height: 181m, Weight: 88kg, Caps: 3
Ben Broster (Saracens), Prop
DoB: 07/05/82, Height: 1.81m, Weight: 105kg, Caps: 2