Query for Sql Server Compact CE

Hi

I have a bit understanding of SQL server compact edition however I am stuck in a query... This is the following input table that I have

StageName TLID Description StageTime WtAvgTime
Stage 1 13065913675Stage1test 10.3 9.5
Stage 2 13072128899 Stage2test 5.5 11
Stage 1 13072328900 Stage2test 9.4 8.4

What I would like to get a cumulative running total (group by StageName) . TLID is incremental as a ID variable in this case... However the running total should be as follows for Stage 1 something like this output

StageName TLID Description StageTime WtAvgTime
Stage 1 13065913675Stage1test 10.3 9.5
Stage 2 13072128899 Stage2test 5.5 11.0 ( Sum of StageTime + WtAvgTime, this will be the same as before)
Stage 1 13072328900 Stage2test 9.4 This should be 18.9 (Sum of StageTime + WtAvgTime - running total)

I would like the WtAvgTime column to be overwritten with the running total query...

Is this possible to achieve in SQL server compact edition as I know this has some limited features regarding queries...?

Can someone help in this context? This is urgent...

Thanks & Regards

Sriram