Value is 10-22MegOhm.
I'd use surface-mounted resistors plus wire. If you can't get 10M, then use two or three 4.7M in series.
Ok, just searched in the lab: I can offer you 10M in SMD size 1206 or 4.7M in SMD size 0805. IIRC at home I have a box in the basement with 20-30 years old stuff, inlcluding assorted resistors -will hav a look there as well.
SMD sizes:
http://en.wikipedia.org/wiki/Surface-mount_technology#Package_sizes
0805 (2013 metric) : 0.08" × 0.05" (2.0 mm × 1.25 mm)
1206 (3216 metric) : 0.126" × 0.063" (3.2 mm × 1.6 mm)