The 30-year-old, who has yet to feature for his parent club this season, is set to complete his move when the loan window re-opens on Saturday.
Jalal told Orient's official website: "I'm delighted to sign. I obviously keep an eye on League One and how the club are doing. I know there's a real good set of players here so I'm just delighted to come into the group and be around the place.
"I know Mathieu Baudry and Marvin Bartley quite well from Bournemouth the last year that they were there. It's nice to have some friendly faces in the training ground.
"It's a really well run club. There's people like Stephen Purches who was at the club who is now a coach at Bournemouth who speaks really highly of the place. 'Purchy' was very beneficial to me in giving me some advice on what it was like and what the fans expect so it was nice to tap into a bit of his knowledge.
"My goals are just to come in, play some games and fit into the team. I know the team are going extremely well. I just want to fit in and achieve what the team are gunning for. You can tell they are all close and my job is to come into the group and integrate as best as I can."