I know what your therapist is asking may seem a bit hard to do. it was for me until my therapist had me think about something....what happens when you dissociated those feelings to begin with? you set them aside by by using your imagination (dissociative)skills.

I looked at my therapist and said what?! and she pulled out her medical dictionary and it said dissociation is disconnecting/separating and here disconnecting and setting something aside means the same thing ...to remove it from what ever its connected to..

I thought about that for a moment and then asked her how do I set aside something that is already set aside that is trying to reconnect?

she told me.. the goal isnt to prevent it from connecting. you have worked hard to regain these repressed memories and now your brain is telling you, that you are ready to handle this memory other wise it would not be trying to reconnect..the problem is that you are getting overwhelmed by the re connection because you have always been disconnected from it. what happens when you rains too hard...flooded... but when it rains slow enough the earth can drink up the rain and crops can grow.. right now the feelings are flooded...how can you slow things down? its your body so only you know what you need in order for these feelings to ease up, slow down, not affect you so much... you can figure this out... and I did..

I used what I already knew about grounding.. when the feelings started getting too hard I turned my attention off of that feeling and on to something that grounds me....rowing my boat on the lake... the more I concentrated on feeling the boat movement, the water sounds, the paddling, the wildlife around the lake the less I felt the hard emotions. I could still feel them.
Imy goal wasnt to totally dissociate from them. my goal was to find a way in which they were no longer affecting me so hard.. I contained those hard feelings in a wall of grounding and breathing exercises. bottom line was its my body and thanks to dissociation in the past I didnt feel those things and in the present I again dont have to feel those things to overwhelming proportions. So I just took control of the situation and contained them in a way that I knew how to do...use my dissociation skills to focus my attention on the grounding and breathing that my therapist taught me for dealing with hard triggering times.

my suggestion talk with your therapist.. they will explain what they mean by containing the emotions so that you are not so overwhelmed and do what ever your therapist has taught you for times when you are triggered, feeling emotional and dealing with things. they are the ones that are treating you.