Toelau has only started in the No.7 jersey once in his 20-game career, playing halfback for Penrith in round four of the 2025 season.
His other five starts have come at hooker, including four since joining the Storm this season.
With Cameron Munster sidelined after knee surgery and Jahrome Hughes troubled by hamstring soreness, Melbourne had little choice but to call on 26-year-old Toelau to partner Tyran Wishart in the halves.
Bellamy said Victorian junior Toelau, who was a standout in the Storm pathway system before two seasons with the Panthers, was a "smart" footballer.
"He's a very smart player, he's got a good kicking game, he's a good defender," the coach said ahead of their final training run.
"We haven't seen a whole leap of him in halves down here, probably more of a dummy-half, but he's just a solid player and he just knows what his strengths are.
"We want them (Toelau and Wishart) to play their best games as individuals, but just to stick to the game plan and that's all we expect."
Bellamy was hopeful Test star Hughes would only miss the one week and return for their round-21 clash with South Sydney.
Hughes himself didn't sound too certain, which would be a massive blow with the 10th-placed Storm still to face the three top-eight teams, including ladder leaders Penrith, in the final rounds.
"It hasn't pulled up very good - I probably shouldn't have played last week and that's solely on me," Hughes said in his 167 podcast.
"I went into the game thinking I was alright, and once I got into the game I had limitations, and I couldn't kick or take off properly, and that's not a good thing as that's my game and I need to be able to do that.
"I should be back next week or the next two weeks."
Melbourne have won eight of their last nine games against the Roosters including an 18-4 victory in round 13, which was one of their best performances of the season.
The Sydneysiders will be without Origin pair, skipper James Tedesco and centre Rob Toia, while Walker and Reece Robson return after being rested last round.
Some have already written off the Storm's chances, given they are four points outside the eight, but Bellamy said his team weren't interested in the opinions of outsiders.
"I don't think these guys take too much notice of people that haven't played the game, never coached the game, so their opinions don't really count," he said."We've prepared the best we can to play the best we can and that's all we worry about doing."
