Near Earth Asteroid 2005 WK4 will came close to Earth on August 9 at 05:02 UT at distance of 0.02 AU (around 8 Earth-Moon distances). It has an estimated diameter of 420 m. The asteroid is currently magnitude 15.5, it reaches mag 14.4 at closest approach then brightens to 14.0 as it moves away. 60 second images will be reasonable when it is below mag 15, 30-10 seconds for 14.5 and brighter.
NEO 2005 WK4 is only visible from the northern iTelescopes as it passes through Perseus, Aries and Pisces. It is moving reasonably fast (33.4"/min), too fast for the tracking capability of the iTelescopes. You will need to use a topocentric ephemeris and camp out on the asteroid track.
The asteroid is high enough to image from around 2:00 am to astronomical twilight from Mayhill and Serpio. Both miss closest approach (in twilight in Spain and too close to the horizon at Mayhill).
Close up view of 2005 WK4 on the night of the 9th form 2:02 am Mayhill. Each time point is 5 minutes. The large rectangle is the field of view of iTelescope 20, small rectangle is the field of view of iTelecope 5 (chart generated with SkyMap pro and the Horizons Track 1.4 add-in (click to embiggen, but use a proper topocentric ephemeris, rather than this chart, for indicative purposes only)).
There is significant parallax effect (423.36"), so unless your planetarium program is able to cope with close parallax (most can't), you will need to work from topocentric coordinates. For topocentric ephemerides go to http://www.minorplanetcenter.net/iau/MPEph/MPEph.html
Nth America MPC Code - H06, Spain MPC Code - I89
Basically, you will need to use unguided exposures. Choose a point where the asteroid will pass and aim at that. Remember that it takes time for the GRAS scopes to get to tracking position. GRAS-14 can take up to 5 minutes (depending on there being reliable stars in the field for tracking), so offset you initial position by around 4 minutes or so (this will be a significant distance) so the asteroid will be in field.