You can reach Imotski:

By car
From Split to Šestanovac by motorway- 58 km 
and from Šestanovac to Imotski by local roadway- 32 km
Total journey time- 1h and 30 min
www.hak.hr

By bus
Total journey time- 2 h 
Split Bus station
www.ak-split.hr
Imotski Bus station
Address: Ulica kralja Zvonimira 75
21260 Imotski
Telephone: +385 (0)21 841 442

By train
By train to Split
www.hznet.hr
By car or by bus from Split to Imotski 

By plane
Split Airport- distance from Split- 25 km
www.split-airport.hr
By car or by bus from Split to Imotski