[1] : WordNet (r) 2.0

painstakingly
     adv : in a fastidious and painstaking manner; "it is almost a
           waste of time painstakingly to learn the routines of
           selling" syn: fastidiously
see also:
fastidiously 

[2] : Moby Thesaurus II by Grady Ward, 1.0

25 moby thesaurus words for "painstakingly":
   assiduously, carefully, cautiously, circumspectly, considerately,
   diligently, dingdong, earnestly, exhaustively, heedfully,
   industriously, intensely, lovingly, meticulously, mindfully,
   regardfully, sedulously, solicitously, tenderly, thoroughgoingly,
   thoroughly, thoughtfully, unremittingly, with care,
   with great care

Painstakingly >> P Words
Painstakingly, definition of term: Painstakingly
painstakingly_pag1.html