http://msdn.microsoft.com/library/default.asp?url=/library/en-us/seccrypto/security/cenroll.asp

; This seems to be the solution, it needs to be tested:
cec.addAttributeToRequest(0,"1.3.6.1.4.1.18506.1.1","THISISAQUALIFIEDREQUEST")

cec.addExtensionToRequest(FALSE,"1.3.6.1.4.1.18506.1.1","THISISAQUALIFIEDREQUEST")

cec.addNameValuePairToRequest(0,"1.3.6.1.4.1.18506.1.1","THISISAQUALIFIEDREQUEST")

; This might help too:
cec.addCertTypeToRequest("qstr:ThisIsAQualifiedRequest")

;For testing:
cec.createFileRequest(XECR_PKCS10_V2_0,DN,OID,"C:\MyRequest.p10")







BOOL     bUEKS;
HRESULT  hr;

// pEnroll is previously instantiated ICEnroll interface pointer

// get the UseExistingKeySet value
hr = pEnroll->get_UseExistingKeySet( &bUEKS );
if (FAILED( hr ))
    printf("Failed get_UseExistingKeySet - %x\n", hr );
else
    printf( "UseExistingKeySet: %d\n", bUEKS );

// set the UseExistingKeySet value
hr = pEnroll->put_UseExistingKeySet( TRUE );
if (FAILED( hr ))
    printf("Failed put_UseExistingKeySet - %x\n", hr );
else
    printf( "UseExistingKeySet set to TRUE\n" );