Houllier remains "comfortable" in a Birmingham hospital after being admitted on Wednesday evening suffering from chest pains.
Assistant boss McAllister, who has taken charge of the team in Houllier's absence, and several of the coaching staff visited Houllier over the weekend.
The players are also planning to visit the former Liverpool boss, who underwent heart surgery during his spell at Anfield a decade ago.
McAllister said: "We are very much in the hands of the specialist. There is a lot of monitoring going on, there are loads of machines in and around Gerard.
"As far as I am concerned, the way I see it, it is a bit early to suggest the length of time he is going to be in there or what the next step is."
Source: PA
Source: PA