The pair, along with club-mates Samson Ma'asi and Alex Coles, were named in the England Under-20s squad earlier this week.
A development camp has been scheduled for this weekend, but Saints will retain the players they want to field against the Falcons.
Dingwall and Sleightholme have both made a big impression in recent weeks, with the former having started the past two Premiership matches at centre and the latter coming off the bench to score in both of those games.
And when asked whether Saints will have them available this weekend, Boyd said: "The players that would be involved in our 23 and play for us will stay with us and the ones that won't will go to camp."
George Furbank is another young player who has caught the eye in recent weeks, but the full-back was forced off after 36 minutes in the 18-13 defeat at Sale Sharks last Saturday.
After the game Boyd said the 22-year-old had suffered a 'shoulder niggle', and Furbank has yet to train this week.
Saints are unlikely to take any risks with him, especially as Ahsee Tuala returned to training at Franklin's Gardens this week following the conclusion of his autumn international commitments with Samoa.
"He (Furbank) didn't train today and we'll wait and see how he comes back tomorrow," Boyd said on Tuesday afternoon.
"He has a chance but we may choose not to risk him because we've got Ahsee Tuala coming back.
"We'll see how we go on that."
Tuala, Dylan Hartley, Courtney Lawes and Dan Biggar were all back in training at the Gardens on Tuesday morning, while Piers Francis will also be available to face the Falcons in the crucial Gallagher Premiership game this weekend.
"It's certainly made a big difference to training this morning to have those guys around," Boyd said.
"We very generously gave them yesterday off and they came back today and they've made a big difference already, bringing good leadership, mentality and setting good standards.