An single engine pilot approaching CGI IFR reported a traffic warning and taking evasive action with an aircraft flying a practice approach to the same airport and under ATC's control. ATC did not provide timely traffic separation.

Narrative

Memphis Center put me on top of a VFR target with me descending IFR in IMC. The flight was to CGI. I left VFR and once clear of the B airspace climbed up to 9;500 FT and activated my IFR flight plan. The usual handoffs and such happened and Memphis Center had me at 3;500 FT about 15 miles out. Three thousand five hundred feet put me right at the tops of the scattered layer with CGI ASOS reporting 2;500 SCT. I let Memphis Center know I was IMC when he called the field at ten miles my 12 O'clock. Since I didn't see the field; Memphis Center turned me first twenty degrees right then HDG 180 and decent to 2;200 FT. This heading had me skirting the edge of the Class D that is CGI. At about this time I noticed a traffic target over the airport as a white diamond (1;600 FT or so I think). I let Memphis Center know I could sometimes see the field through the breaks in the clouds. As I continued my decent Memphis Center told me to turn right to 090 so I repeated that back and commenced my turn. This turn would have put me basically on a five mile final for Runway 10 which is 6;500 FT and easy to see. Right as I started to turn right at about 2;500 FT I hear 'TRAFFIC! TRAFFIC!'; So I looked at the #2 Garmin (which I leave on the traffic page) and sure enough there is traffic under me at I think 400 FT. I pulled up and told Memphis Center that I was IMC and getting traffic alerts from a target 200 FT; which is what the solid yellow circle had next to it at the time. Memphis said something about the target being to my left but his radar has delay. I told Memphis Center I showed it to my right and I was going up and right then I popped out of the cloud. Memphis Center then must have seen the traffic to my right because he turned me left toward the field. I was looking for traffic and the field was right there to my left at about eight O'clock. I told Memphis I could see the field and he told me we were 'divergent'; gave me a clearance for the visual approach to Runway 20 and switched me to Tower. As I called Tower with position five miles southwest inbound Runway 20 Tower asked me again for my position which I restated as then just going over a local landmark (three mile hill) and Tower warned me of VFR traffic going out to the practice ILS 10 approach. I let Tower know I had the traffic alert in the clouds as 200 FT below me and now he was behind me. So Tower cleared me to land Runway 10 and I accepted. I then spent some time talking to the Controller and getting the number of the other pilot and his tail number. The other pilot shot that one approach and left the area VFR but then called the Tower some time later to tell the Tower he was at 1;900 FT and the ASOS was reporting 2;500 FT. He also said that after he left the area he climbed up and the bases were at 2;600 FT.