This should be pretty straightforward.

Just copy the source code query_GAIA_DR2.F from this website, 
along with the two database files (they're big).

To compile it, just type 

   "gfortran query_GAIA_DR2.F -o query_GAIA_DR2.e <cr>"

Then execute it.  If you run it with no arguments, it'll tell
you the arguments it needs.  There are several different ways
to run it:
  1) give it an RA/Dec and radius, and it'll return a cone search
     (if you want, it'll push the results into an HST-like frame)
  2) give it a list of GAIA IDs
  3) give it a list of RAs and Decs and it will return the closest star
  4) full-sky search (you can restrict things by min/max parameters)
  

./query_GAIA_DR2.e <cr>
  
 There are currently FIVE ways to run:   
  
  
 OPTION#1 ---  cone search 
  
     3+ args:  RA_CEN=RA DE_CEN=Dec RAD=rad (deg)   
               [DIAG+]  
               [RV+] 
               ["XY(XCEN,YCEN,PIX_SCL,RDATE)"]
  
                       with 
  
                       RA  - SEXIG or DECIMAL 
                       Dec - SEXIG or DECIMAL 
                                              
  
 examples: 
  
 ./query_GAIA_DR2.e "RA_CEN=00:24:05.359"   \
                    "DE_CEN=-72:04:53.20"   \
                     RAD=1.0
  
 ./query_GAIA_DR2.e "RA_CEN=00:24:05.359"      \
                     "DE_CEN=-72:04:53.20"     \
                      RAD=0.075                \
                     "XY(5000,5000,50,2017.3)" 
  
                     (make a frame with the ACS SCALE) 
                     (needs to be in quotes to prevent 
                                         parser error) 
                     (I have not yet double-checked the
                         time-pushing; need to add PI) 
  
 --------
  
 OPTION#2 --- list of ra/decs  
  
    ./query_GAIA.e LISTRD=TXT.RDML  (list of ra/dec)
  
 --------
  
 OPTION#3 ---  
  
    ./query_GAIA.e LISTID=xxxxxxxxxx (can be a single
                                       GAIA ID number
                                  or a file with list
                                          of numbers)
                                                     
 --------
  
 OPTION#4 ---  
  
 query_gaia_DR2:  1 arg (box):
  
    ./query_GAIA.e BOX=RA1,RA2,DE1,DE2  (in deg)
  
                  can specify command-line delimiters,
                  such as:  
  
                    "ePI_MAXU=0.1" 
                     etc           
  
 --------
  
 OPTION#5 ---  
  
    ./query_GAIA.e DUMP   (ouptuts the whole catalog; 
                           you can modify the code    
                           to output the stars that   
                           you want; ask Jay if you   
                           need help with the FORTRAN)
  
                  can specify command-line delimiters,
                  such as:  
  
                     "ePI_MAXU=0.1"   
                     etc              
        example ./query_GAIA_DR2.e DUMP             \
                                   EPI_MAXU=0.10000 \
                                   EPI_MINU=0.00001  
  
 ----------------------------------------------------
  
 List of delimeters: 
  
         RA_MINU   RA_MAXU   ERA_MINU   ERA_MAXU
         DE_MINU   DE_MAXU   EDE_MINU   EDE_MAXU
         MG_MINU   MG_MAXU   EMG_MINU   EMG_MAXU
         MB_MINU   MB_MAXU   EMB_MINU   EMB_MAXU
         MR_MINU   MR_MAXU   EMR_MINU   EMR_MAXU
       MURA_MINU MURA_MAXU EMURA_MINU EMURA_MAXU
       MUDE_MINU MUDE_MAXU EMUDE_MINU EMUDE_MAXU
         PI_MINU   PI_MAXU   EPI_MINU   EPI_MAXU
       NVIS_MINU NVIS_MAXU  NMAT_MINU  NMAT_MAXU
       IGOF_MINU IGOF_MAXU  IXSN_MINU  IXSN_MAXU
       NBAD_MINU NBAD_MAXU  NGUD_MINU  NGUD_MAXU
       UFLG_MINU UFLG_MAXU  GFLG_MINU  GFLG_MAXU
       RFLG_MINU RFLG_MAXU                      
         RV_MINU   RV_MAXU   ERV_MINU   ERV_MAXU
  
       And colors:  
        BmG_MINU  BmG_MAXU   BmR_MINU   BmR_MAXU
                             GmR_MINU   GmR_MAXU
  
  
 It outputs to STDOUT the data.
  
 The routine also reports the star number (in this
 list) and the tangent-plane offset in RA, Dec and
 the total offset (all in degrees).