Anier took his tally for the season to seven with emphatic strikes in each half and Ainsworth coolly finished off a well-worked move in between as Motherwell secured their 10th Scottish Premiership win at Fir Park.
McCall is "fairly confident" he can keep both players, whose loan spells end in the first two weeks of 2014, although Anier is unsure whether Viking Stavanger will allow him to go out on loan again with one year left on his contract.
McCall said: "Without stating the obvious, going out of the cup competitions has not helped the finances so we have to make sure what we do is for the best for the club, but it's not as if we would be breaking the bank.
"We would like to keep Henri and Lionel - I thought Lionel had his best game for us - we have had tentative discussions with their agent. We now need to have discussions with (directors) Leeann (Dempster) and Derek (Weir), but that might just have twisted their arm."
On Anier, McCall added: "We aren't paying his full wages at the moment so that's where the stumbling block could be. If we could pay him the same salary now as we have done then I think we will be able to keep him."
Both players are keen to stay. Anier, who was watched by his close friend and Estonia team-mate, the former Motherwell striker Henrik Ojamaa, said: "I have been around a few clubs so it would be nice to stay and get something permanent or at least to stay until the end of the season. I have really enjoyed my time here.
"It's between the clubs, I can't do anything, but hopefully something will get sorted in the next two weeks."
On-loan Rotherham winger Ainsworth netted his second goal for the club and was a constant threat down the right wing.
McCall said: "He had little niggles and has not played a lot of 90 minutes but I thought he was terrific. He took his goal really well and he's another one who would like to stay, and hopefully we can do that as well."
St Mirren manager Danny Lennon felt his side had dropped below their recent standards.
"The highly frustrating part is that we have dropped one or two gears in terms of our work ethic, and that has been the main ingredient of our success," he said.
"I just felt we were off, we played second fiddle to a lot of balls and Motherwell just showed a greater hunger.
"That disappoints me and it hurts me to say that."